3 SPDX-License-Identifier: BSD-2-Clause
5 Copyright (c) 2018-2021 Gavin D. Howard and contributors.
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10 * Redistributions of source code must retain the above copyright notice, this
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14 this list of conditions and the following disclaimer in the documentation
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33 bc - arbitrary-precision decimal arithmetic language and calculator
37 **bc** [**-ghilPqRsvVw**] [**-\-global-stacks**] [**-\-help**] [**-\-interactive**] [**-\-mathlib**] [**-\-no-prompt**] [**-\-no-read-prompt**] [**-\-quiet**] [**-\-standard**] [**-\-warn**] [**-\-version**] [**-e** *expr*] [**-\-expression**=*expr*...] [**-f** *file*...] [**-\-file**=*file*...] [*file*...]
41 bc(1) is an interactive processor for a language first standardized in 1991 by
42 POSIX. (The current standard is [here][1].) The language provides unlimited
43 precision decimal arithmetic and is somewhat C-like, but there are differences.
44 Such differences will be noted in this document.
46 After parsing and handling options, this bc(1) reads any files given on the
47 command line and executes them before reading from **stdin**.
49 This bc(1) is a drop-in replacement for *any* bc(1), including (and
50 especially) the GNU bc(1). It also has many extensions and extra features beyond
51 other implementations.
55 The following are the options that bc(1) accepts.
57 **-g**, **-\-global-stacks**
59 : Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
61 This has the effect that a copy of the current value of all four are pushed
62 onto a stack for every function call, as well as popped when every function
63 returns. This means that functions can assign to any and all of those
64 globals without worrying that the change will affect other functions.
65 Thus, a hypothetical function named **output(x,b)** that simply printed
66 **x** in base **b** could be written like this:
68 define void output(x, b) {
75 define void output(x, b) {
83 This makes writing functions much easier.
85 (**Note**: the function **output(x,b)** exists in the extended math library.
86 See the **LIBRARY** section.)
88 However, since using this flag means that functions cannot set **ibase**,
89 **obase**, **scale**, or **seed** globally, functions that are made to do so
90 cannot work anymore. There are two possible use cases for that, and each has
93 First, if a function is called on startup to turn bc(1) into a number
94 converter, it is possible to replace that capability with various shell
97 alias d2o="bc -e ibase=A -e obase=8"
98 alias h2b="bc -e ibase=G -e obase=2"
100 Second, if the purpose of a function is to set **ibase**, **obase**,
101 **scale**, or **seed** globally for any other purpose, it could be split
102 into one to four functions (based on how many globals it sets) and each of
103 those functions could return the desired value for a global.
105 For functions that set **seed**, the value assigned to **seed** is not
106 propagated to parent functions. This means that the sequence of
107 pseudo-random numbers that they see will not be the same sequence of
108 pseudo-random numbers that any parent sees. This is only the case once
109 **seed** has been set.
111 If a function desires to not affect the sequence of pseudo-random numbers
112 of its parents, but wants to use the same **seed**, it can use the following
117 If the behavior of this option is desired for every run of bc(1), then users
118 could make sure to define **BC_ENV_ARGS** and include this option (see the
119 **ENVIRONMENT VARIABLES** section for more details).
121 If **-s**, **-w**, or any equivalents are used, this option is ignored.
123 This is a **non-portable extension**.
127 : Prints a usage message and quits.
129 **-i**, **-\-interactive**
131 : Forces interactive mode. (See the **INTERACTIVE MODE** section.)
133 This is a **non-portable extension**.
135 **-l**, **-\-mathlib**
137 : Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
138 math library and the extended math library before running any code,
139 including any expressions or files specified on the command line.
141 To learn what is in the libraries, see the **LIBRARY** section.
143 **-P**, **-\-no-prompt**
145 : This option is a no-op.
147 This is a **non-portable extension**.
149 **-R**, **-\-no-read-prompt**
151 : Because bc(1) was built without support for prompts, this option is a no-op.
153 This is a **non-portable extension**.
157 : This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
158 Without this option, GNU bc(1) prints a copyright header. This bc(1) only
159 prints the copyright header if one or more of the **-v**, **-V**, or
160 **-\-version** options are given.
162 This is a **non-portable extension**.
164 **-s**, **-\-standard**
166 : Process exactly the language defined by the [standard][1] and error if any
169 This is a **non-portable extension**.
171 **-v**, **-V**, **-\-version**
173 : Print the version information (copyright header) and exit.
175 This is a **non-portable extension**.
179 : Like **-s** and **-\-standard**, except that warnings (and not errors) are
180 printed for non-standard extensions and execution continues normally.
182 This is a **non-portable extension**.
184 **-e** *expr*, **-\-expression**=*expr*
186 : Evaluates *expr*. If multiple expressions are given, they are evaluated in
187 order. If files are given as well (see below), the expressions and files are
188 evaluated in the order given. This means that if a file is given before an
189 expression, the file is read in and evaluated first.
191 If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
192 see the **ENVIRONMENT VARIABLES** section), then after processing all
193 expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
194 as an argument at least once to **-f** or **-\-file**, whether on the
195 command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
196 **-\-expression**, **-f**, or **-\-file** arguments are given after **-f-**
197 or equivalent is given, bc(1) will give a fatal error and exit.
199 This is a **non-portable extension**.
201 **-f** *file*, **-\-file**=*file*
203 : Reads in *file* and evaluates it, line by line, as though it were read
204 through **stdin**. If expressions are also given (see above), the
205 expressions are evaluated in the order given.
207 If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
208 see the **ENVIRONMENT VARIABLES** section), then after processing all
209 expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
210 as an argument at least once to **-f** or **-\-file**. However, if any other
211 **-e**, **-\-expression**, **-f**, or **-\-file** arguments are given after
212 **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
214 This is a **non-portable extension**.
216 All long options are **non-portable extensions**.
220 Any non-error output is written to **stdout**. In addition, if history (see the
221 **HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
222 both are output to **stdout**.
224 **Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
225 error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
226 **stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
227 is done so that bc(1) can report problems when **stdout** is redirected to a
230 If there are scripts that depend on the behavior of other bc(1) implementations,
231 it is recommended that those scripts be changed to redirect **stdout** to
236 Any error output is written to **stderr**.
238 **Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
239 error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
240 **stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
241 is done so that bc(1) can exit with an error code when **stderr** is redirected
244 If there are scripts that depend on the behavior of other bc(1) implementations,
245 it is recommended that those scripts be changed to redirect **stderr** to
250 The syntax for bc(1) programs is mostly C-like, with some differences. This
251 bc(1) follows the [POSIX standard][1], which is a much more thorough resource
252 for the language this bc(1) accepts. This section is meant to be a summary and a
253 listing of all the extensions to the standard.
255 In the sections below, **E** means expression, **S** means statement, and **I**
258 Identifiers (**I**) start with a lowercase letter and can be followed by any
259 number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
260 (**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
261 Identifiers with more than one character (letter) are a
262 **non-portable extension**.
264 **ibase** is a global variable determining how to interpret constant numbers. It
265 is the "input" base, or the number base used for interpreting input numbers.
266 **ibase** is initially **10**. If the **-s** (**-\-standard**) and **-w**
267 (**-\-warn**) flags were not given on the command line, the max allowable value
268 for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
269 **ibase** is **2**. The max allowable value for **ibase** can be queried in
270 bc(1) programs with the **maxibase()** built-in function.
272 **obase** is a global variable determining how to output results. It is the
273 "output" base, or the number base used for outputting numbers. **obase** is
274 initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
275 can be queried in bc(1) programs with the **maxobase()** built-in function. The
276 min allowable value for **obase** is **0**. If **obase** is **0**, values are
277 output in scientific notation, and if **obase** is **1**, values are output in
278 engineering notation. Otherwise, values are output in the specified base.
280 Outputting in scientific and engineering notations are **non-portable
283 The *scale* of an expression is the number of digits in the result of the
284 expression right of the decimal point, and **scale** is a global variable that
285 sets the precision of any operations, with exceptions. **scale** is initially
286 **0**. **scale** cannot be negative. The max allowable value for **scale** is
287 **BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
290 bc(1) has both *global* variables and *local* variables. All *local*
291 variables are local to the function; they are parameters or are introduced in
292 the **auto** list of a function (see the **FUNCTIONS** section). If a variable
293 is accessed which is not a parameter or in the **auto** list, it is assumed to
294 be *global*. If a parent function has a *local* variable version of a variable
295 that a child function considers *global*, the value of that *global* variable in
296 the child function is the value of the variable in the parent function, not the
297 value of the actual *global* variable.
299 All of the above applies to arrays as well.
301 The value of a statement that is an expression (i.e., any of the named
302 expressions or operands) is printed unless the lowest precedence operator is an
303 assignment operator *and* the expression is notsurrounded by parentheses.
305 The value that is printed is also assigned to the special variable **last**. A
306 single dot (**.**) may also be used as a synonym for **last**. These are
307 **non-portable extensions**.
309 Either semicolons or newlines may separate statements.
313 There are two kinds of comments:
315 1. Block comments are enclosed in **/\*** and **\*/**.
316 2. Line comments go from **#** until, and not including, the next newline. This
317 is a **non-portable extension**.
321 The following are named expressions in bc(1):
324 2. Array Elements: **I[E]**
329 7. **last** or a single dot (**.**)
331 Numbers 6 and 7 are **non-portable extensions**.
333 The meaning of **seed** is dependent on the current pseudo-random number
334 generator but is guaranteed to not change except for new major versions.
336 The *scale* and sign of the value may be significant.
338 If a previously used **seed** value is assigned to **seed** and used again, the
339 pseudo-random number generator is guaranteed to produce the same sequence of
340 pseudo-random numbers as it did when the **seed** value was previously used.
342 The exact value assigned to **seed** is not guaranteed to be returned if
343 **seed** is queried again immediately. However, if **seed** *does* return a
344 different value, both values, when assigned to **seed**, are guaranteed to
345 produce the same sequence of pseudo-random numbers. This means that certain
346 values assigned to **seed** will *not* produce unique sequences of pseudo-random
347 numbers. The value of **seed** will change after any use of the **rand()** and
348 **irand(E)** operands (see the *Operands* subsection below), except if the
349 parameter passed to **irand(E)** is **0**, **1**, or negative.
351 There is no limit to the length (number of significant decimal digits) or
352 *scale* of the value that can be assigned to **seed**.
354 Variables and arrays do not interfere; users can have arrays named the same as
355 variables. This also applies to functions (see the **FUNCTIONS** section), so a
356 user can have a variable, array, and function that all have the same name, and
357 they will not shadow each other, whether inside of functions or not.
359 Named expressions are required as the operand of **increment**/**decrement**
360 operators and as the left side of **assignment** operators (see the *Operators*
365 The following are valid operands in bc(1):
367 1. Numbers (see the *Numbers* subsection below).
368 2. Array indices (**I[E]**).
369 3. **(E)**: The value of **E** (used to change precedence).
370 4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
371 5. **length(E)**: The number of significant decimal digits in **E**.
372 6. **length(I[])**: The number of elements in the array **I**. This is a
373 **non-portable extension**.
374 7. **scale(E)**: The *scale* of **E**.
375 8. **abs(E)**: The absolute value of **E**. This is a **non-portable
377 9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
378 a non-**void** function (see the *Void Functions* subsection of the
379 **FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
380 **I[]**, which will automatically be turned into array references (see the
381 *Array References* subsection of the **FUNCTIONS** section) if the
382 corresponding parameter in the function definition is an array reference.
383 10. **read()**: Reads a line from **stdin** and uses that as an expression. The
384 result of that expression is the result of the **read()** operand. This is a
385 **non-portable extension**.
386 11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
388 12. **maxobase()**: The max allowable **obase**. This is a **non-portable
390 13. **maxscale()**: The max allowable **scale**. This is a **non-portable
392 14. **rand()**: A pseudo-random integer between **0** (inclusive) and
393 **BC_RAND_MAX** (inclusive). Using this operand will change the value of
394 **seed**. This is a **non-portable extension**.
395 15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
396 value of **E** (exclusive). If **E** is negative or is a non-integer
397 (**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
398 the **RESET** section) while **seed** remains unchanged. If **E** is larger
399 than **BC_RAND_MAX**, the higher bound is honored by generating several
400 pseudo-random integers, multiplying them by appropriate powers of
401 **BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
402 can be generated with this operand is unbounded. Using this operand will
403 change the value of **seed**, unless the value of **E** is **0** or **1**.
404 In that case, **0** is returned, and **seed** is *not* changed. This is a
405 **non-portable extension**.
406 16. **maxrand()**: The max integer returned by **rand()**. This is a
407 **non-portable extension**.
409 The integers generated by **rand()** and **irand(E)** are guaranteed to be as
410 unbiased as possible, subject to the limitations of the pseudo-random number
413 **Note**: The values returned by the pseudo-random number generator with
414 **rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
415 This is a consequence of using a seeded pseudo-random number generator. However,
416 they *are* guaranteed to be reproducible with identical **seed** values. This
417 means that the pseudo-random values from bc(1) should only be used where a
418 reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
419 use a non-seeded pseudo-random number generator.
423 Numbers are strings made up of digits, uppercase letters, and at most **1**
424 period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
425 letters are equal to **9** + their position in the alphabet (i.e., **A** equals
426 **10**, or **9+1**). If a digit or letter makes no sense with the current value
427 of **ibase**, they are set to the value of the highest valid digit in **ibase**.
429 Single-character numbers (i.e., **A** alone) take the value that they would have
430 if they were valid digits, regardless of the value of **ibase**. This means that
431 **A** alone always equals decimal **10** and **Z** alone always equals decimal
434 In addition, bc(1) accepts numbers in scientific notation. These have the form
435 **\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
436 an integer. An example is **1.89237e9**, which is equal to **1892370000**.
437 Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
439 Using scientific notation is an error or warning if the **-s** or **-w**,
440 respectively, command-line options (or equivalents) are given.
442 **WARNING**: Both the number and the exponent in scientific notation are
443 interpreted according to the current **ibase**, but the number is still
444 multiplied by **10\^exponent** regardless of the current **ibase**. For example,
445 if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
446 resulting decimal number will be **2550000000000**, and if bc(1) is given the
447 number string **10e-4**, the resulting decimal number will be **0.0016**.
449 Accepting input as scientific notation is a **non-portable extension**.
453 The following arithmetic and logical operators can be used. They are listed in
454 order of decreasing precedence. Operators in the same group have the same
459 : Type: Prefix and Postfix
463 Description: **increment**, **decrement**
471 Description: **negation**, **boolean not**
479 Description: **truncation**
487 Description: **set precision**
495 Description: **power**
503 Description: **multiply**, **divide**, **modulus**
511 Description: **add**, **subtract**
519 Description: **shift left**, **shift right**
521 **=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
527 Description: **assignment**
529 **==** **\<=** **\>=** **!=** **\<** **\>**
535 Description: **relational**
543 Description: **boolean and**
551 Description: **boolean or**
553 The operators will be described in more detail below.
557 : The prefix and postfix **increment** and **decrement** operators behave
558 exactly like they would in C. They require a named expression (see the
559 *Named Expressions* subsection) as an operand.
561 The prefix versions of these operators are more efficient; use them where
566 : The **negation** operator returns **0** if a user attempts to negate any
567 expression with the value **0**. Otherwise, a copy of the expression with
568 its sign flipped is returned.
572 : The **boolean not** operator returns **1** if the expression is **0**, or
575 This is a **non-portable extension**.
579 : The **truncation** operator returns a copy of the given expression with all
580 of its *scale* removed.
582 This is a **non-portable extension**.
586 : The **set precision** operator takes two expressions and returns a copy of
587 the first with its *scale* equal to the value of the second expression. That
588 could either mean that the number is returned without change (if the
589 *scale* of the first expression matches the value of the second
590 expression), extended (if it is less), or truncated (if it is more).
592 The second expression must be an integer (no *scale*) and non-negative.
594 This is a **non-portable extension**.
598 : The **power** operator (not the **exclusive or** operator, as it would be in
599 C) takes two expressions and raises the first to the power of the value of
600 the second. The *scale* of the result is equal to **scale**.
602 The second expression must be an integer (no *scale*), and if it is
603 negative, the first value must be non-zero.
607 : The **multiply** operator takes two expressions, multiplies them, and
608 returns the product. If **a** is the *scale* of the first expression and
609 **b** is the *scale* of the second expression, the *scale* of the result is
610 equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
615 : The **divide** operator takes two expressions, divides them, and returns the
616 quotient. The *scale* of the result shall be the value of **scale**.
618 The second expression must be non-zero.
622 : The **modulus** operator takes two expressions, **a** and **b**, and
623 evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
624 result of step 1 to calculate **a-(a/b)\*b** to *scale*
625 **max(scale+scale(b),scale(a))**.
627 The second expression must be non-zero.
631 : The **add** operator takes two expressions, **a** and **b**, and returns the
632 sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
636 : The **subtract** operator takes two expressions, **a** and **b**, and
637 returns the difference, with a *scale* equal to the max of the *scale*s of
642 : The **left shift** operator takes two expressions, **a** and **b**, and
643 returns a copy of the value of **a** with its decimal point moved **b**
646 The second expression must be an integer (no *scale*) and non-negative.
648 This is a **non-portable extension**.
652 : The **right shift** operator takes two expressions, **a** and **b**, and
653 returns a copy of the value of **a** with its decimal point moved **b**
656 The second expression must be an integer (no *scale*) and non-negative.
658 This is a **non-portable extension**.
660 **=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
662 : The **assignment** operators take two expressions, **a** and **b** where
663 **a** is a named expression (see the *Named Expressions* subsection).
665 For **=**, **b** is copied and the result is assigned to **a**. For all
666 others, **a** and **b** are applied as operands to the corresponding
667 arithmetic operator and the result is assigned to **a**.
669 The **assignment** operators that correspond to operators that are
670 extensions are themselves **non-portable extensions**.
672 **==** **\<=** **\>=** **!=** **\<** **\>**
674 : The **relational** operators compare two expressions, **a** and **b**, and
675 if the relation holds, according to C language semantics, the result is
676 **1**. Otherwise, it is **0**.
678 Note that unlike in C, these operators have a lower precedence than the
679 **assignment** operators, which means that **a=b\>c** is interpreted as
682 Also, unlike the [standard][1] requires, these operators can appear anywhere
683 any other expressions can be used. This allowance is a
684 **non-portable extension**.
688 : The **boolean and** operator takes two expressions and returns **1** if both
689 expressions are non-zero, **0** otherwise.
691 This is *not* a short-circuit operator.
693 This is a **non-portable extension**.
697 : The **boolean or** operator takes two expressions and returns **1** if one
698 of the expressions is non-zero, **0** otherwise.
700 This is *not* a short-circuit operator.
702 This is a **non-portable extension**.
706 The following items are statements:
709 2. **{** **S** **;** ... **;** **S** **}**
710 3. **if** **(** **E** **)** **S**
711 4. **if** **(** **E** **)** **S** **else** **S**
712 5. **while** **(** **E** **)** **S**
713 6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
714 7. An empty statement
720 13. A string of characters, enclosed in double quotes
721 14. **print** **E** **,** ... **,** **E**
722 15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
723 a **void** function (see the *Void Functions* subsection of the
724 **FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
725 **I[]**, which will automatically be turned into array references (see the
726 *Array References* subsection of the **FUNCTIONS** section) if the
727 corresponding parameter in the function definition is an array reference.
729 Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
731 Also, as a **non-portable extension**, any or all of the expressions in the
732 header of a for loop may be omitted. If the condition (second expression) is
733 omitted, it is assumed to be a constant **1**.
735 The **break** statement causes a loop to stop iterating and resume execution
736 immediately following a loop. This is only allowed in loops.
738 The **continue** statement causes a loop iteration to stop early and returns to
739 the start of the loop, including testing the loop condition. This is only
742 The **if** **else** statement does the same thing as in C.
744 The **quit** statement causes bc(1) to quit, even if it is on a branch that will
745 not be executed (it is a compile-time command).
747 The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
748 if it is on a branch of an **if** statement that is not executed, bc(1) does not
751 The **limits** statement prints the limits that this bc(1) is subject to. This
752 is like the **quit** statement in that it is a compile-time command.
754 An expression by itself is evaluated and printed, followed by a newline.
756 Both scientific notation and engineering notation are available for printing the
757 results of expressions. Scientific notation is activated by assigning **0** to
758 **obase**, and engineering notation is activated by assigning **1** to
759 **obase**. To deactivate them, just assign a different value to **obase**.
761 Scientific notation and engineering notation are disabled if bc(1) is run with
762 either the **-s** or **-w** command-line options (or equivalents).
764 Printing numbers in scientific notation and/or engineering notation is a
765 **non-portable extension**.
769 The "expressions" in a **print** statement may also be strings. If they are, there
770 are backslash escape sequences that are interpreted specially. What those
771 sequences are, and what they cause to be printed, are shown below:
785 Any other character following a backslash causes the backslash and character to
788 Any non-string expression in a print statement shall be assigned to **last**,
789 like any other expression that is printed.
791 ## Order of Evaluation
793 All expressions in a statment are evaluated left to right, except as necessary
794 to maintain order of operations. This means, for example, assuming that **i** is
795 equal to **0**, in the expression
799 the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
800 at the end of the expression.
802 This includes function arguments. Thus, assuming **i** is equal to **0**, this
803 means that in the expression
807 the first argument passed to **x()** is **0**, and the second argument is **1**,
808 while **i** is equal to **2** before the function starts executing.
812 Function definitions are as follows:
822 Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
823 make a parameter or **auto** var an array, and any **I** in the parameter list
824 may be replaced with **\*I[]** to make a parameter an array reference. Callers
825 of functions that take array references should not put an asterisk in the call;
826 they must be called with just **I[]** like normal array parameters and will be
827 automatically converted into references.
829 As a **non-portable extension**, the opening brace of a **define** statement may
830 appear on the next line.
832 As a **non-portable extension**, the return statement may also be in one of the
836 2. **return** **(** **)**
839 The first two, or not specifying a **return** statement, is equivalent to
840 **return (0)**, unless the function is a **void** function (see the *Void
841 Functions* subsection below).
845 Functions can also be **void** functions, defined as follows:
848 define void I(I,...,I){
855 They can only be used as standalone expressions, where such an expression would
856 be printed alone, except in a print statement.
858 Void functions can only use the first two **return** statements listed above.
859 They can also omit the return statement entirely.
861 The word "void" is not treated as a keyword; it is still possible to have
862 variables, arrays, and functions named **void**. The word "void" is only
863 treated specially right after the **define** keyword.
865 This is a **non-portable extension**.
869 For any array in the parameter list, if the array is declared in the form
875 it is a **reference**. Any changes to the array in the function are reflected,
876 when the function returns, to the array that was passed in.
878 Other than this, all function arguments are passed by value.
880 This is a **non-portable extension**.
884 All of the functions below, including the functions in the extended math
885 library (see the *Extended Library* subsection below), are available when the
886 **-l** or **-\-mathlib** command-line flags are given, except that the extended
887 math library is not available when the **-s** option, the **-w** option, or
888 equivalents are given.
892 The [standard][1] defines the following functions for the math library:
896 : Returns the sine of **x**, which is assumed to be in radians.
898 This is a transcendental function (see the *Transcendental Functions*
903 : Returns the cosine of **x**, which is assumed to be in radians.
905 This is a transcendental function (see the *Transcendental Functions*
910 : Returns the arctangent of **x**, in radians.
912 This is a transcendental function (see the *Transcendental Functions*
917 : Returns the natural logarithm of **x**.
919 This is a transcendental function (see the *Transcendental Functions*
924 : Returns the mathematical constant **e** raised to the power of **x**.
926 This is a transcendental function (see the *Transcendental Functions*
931 : Returns the bessel integer order **n** (truncated) of **x**.
933 This is a transcendental function (see the *Transcendental Functions*
938 The extended library is *not* loaded when the **-s**/**-\-standard** or
939 **-w**/**-\-warn** options are given since they are not part of the library
940 defined by the [standard][1].
942 The extended library is a **non-portable extension**.
946 : Calculates **x** to the power of **y**, even if **y** is not an integer, and
947 returns the result to the current **scale**.
949 It is an error if **y** is negative and **x** is **0**.
951 This is a transcendental function (see the *Transcendental Functions*
956 : Returns **x** rounded to **p** decimal places according to the rounding mode
957 [round half away from **0**][3].
961 : Returns **x** rounded to **p** decimal places according to the rounding mode
962 [round away from **0**][6].
966 : Returns the factorial of the truncated absolute value of **x**.
970 : Returns the permutation of the truncated absolute value of **n** of the
971 truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
975 : Returns the combination of the truncated absolute value of **n** of the
976 truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
980 : Returns the logarithm base **2** of **x**.
982 This is a transcendental function (see the *Transcendental Functions*
987 : Returns the logarithm base **10** of **x**.
989 This is a transcendental function (see the *Transcendental Functions*
994 : Returns the logarithm base **b** of **x**.
996 This is a transcendental function (see the *Transcendental Functions*
1001 : Returns the cube root of **x**.
1005 : Calculates the truncated value of **n**, **r**, and returns the **r**th root
1006 of **x** to the current **scale**.
1008 If **r** is **0** or negative, this raises an error and causes bc(1) to
1009 reset (see the **RESET** section). It also raises an error and causes bc(1)
1010 to reset if **r** is even and **x** is negative.
1014 : Returns **pi** to **p** decimal places.
1016 This is a transcendental function (see the *Transcendental Functions*
1021 : Returns the tangent of **x**, which is assumed to be in radians.
1023 This is a transcendental function (see the *Transcendental Functions*
1028 : Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
1029 equal to **0**, it raises an error and causes bc(1) to reset (see the
1030 **RESET** section). Otherwise, if **x** is greater than **0**, it returns
1031 **a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
1032 to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
1033 is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
1034 and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
1035 **0**, and **y** is less than **0**, it returns **-pi/2**.
1037 This function is the same as the **atan2()** function in many programming
1040 This is a transcendental function (see the *Transcendental Functions*
1045 : Returns the sine of **x**, which is assumed to be in radians.
1047 This is an alias of **s(x)**.
1049 This is a transcendental function (see the *Transcendental Functions*
1054 : Returns the cosine of **x**, which is assumed to be in radians.
1056 This is an alias of **c(x)**.
1058 This is a transcendental function (see the *Transcendental Functions*
1063 : Returns the tangent of **x**, which is assumed to be in radians.
1065 If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
1066 to reset (see the **RESET** section).
1068 This is an alias of **t(x)**.
1070 This is a transcendental function (see the *Transcendental Functions*
1075 : Returns the arctangent of **x**, in radians.
1077 This is an alias of **a(x)**.
1079 This is a transcendental function (see the *Transcendental Functions*
1084 : Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
1085 equal to **0**, it raises an error and causes bc(1) to reset (see the
1086 **RESET** section). Otherwise, if **x** is greater than **0**, it returns
1087 **a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
1088 to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
1089 is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
1090 and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
1091 **0**, and **y** is less than **0**, it returns **-pi/2**.
1093 This function is the same as the **atan2()** function in many programming
1096 This is an alias of **a2(y, x)**.
1098 This is a transcendental function (see the *Transcendental Functions*
1103 : Converts **x** from radians to degrees and returns the result.
1105 This is a transcendental function (see the *Transcendental Functions*
1110 : Converts **x** from degrees to radians and returns the result.
1112 This is a transcendental function (see the *Transcendental Functions*
1117 : Generates a pseudo-random number between **0** (inclusive) and **1**
1118 (exclusive) with the number of decimal digits after the decimal point equal
1119 to the truncated absolute value of **p**. If **p** is not **0**, then
1120 calling this function will change the value of **seed**. If **p** is **0**,
1121 then **0** is returned, and **seed** is *not* changed.
1125 : Generates a pseudo-random number that is between **0** (inclusive) and the
1126 truncated absolute value of **i** (exclusive) with the number of decimal
1127 digits after the decimal point equal to the truncated absolute value of
1128 **p**. If the absolute value of **i** is greater than or equal to **2**, and
1129 **p** is not **0**, then calling this function will change the value of
1130 **seed**; otherwise, **0** is returned and **seed** is not changed.
1134 : Returns **x** with its sign flipped with probability **0.5**. In other
1135 words, it randomizes the sign of **x**.
1139 : Returns a random boolean value (either **0** or **1**).
1143 : Returns the numbers of unsigned integer bytes required to hold the truncated
1144 absolute value of **x**.
1148 : Returns the numbers of signed, two's-complement integer bytes required to
1149 hold the truncated value of **x**.
1153 : Outputs the hexadecimal (base **16**) representation of **x**.
1155 This is a **void** function (see the *Void Functions* subsection of the
1156 **FUNCTIONS** section).
1160 : Outputs the binary (base **2**) representation of **x**.
1162 This is a **void** function (see the *Void Functions* subsection of the
1163 **FUNCTIONS** section).
1167 : Outputs the base **b** representation of **x**.
1169 This is a **void** function (see the *Void Functions* subsection of the
1170 **FUNCTIONS** section).
1174 : Outputs the representation, in binary and hexadecimal, of **x** as an
1175 unsigned integer in as few power of two bytes as possible. Both outputs are
1176 split into bytes separated by spaces.
1178 If **x** is not an integer or is negative, an error message is printed
1179 instead, but bc(1) is not reset (see the **RESET** section).
1181 This is a **void** function (see the *Void Functions* subsection of the
1182 **FUNCTIONS** section).
1186 : Outputs the representation, in binary and hexadecimal, of **x** as a signed,
1187 two's-complement integer in as few power of two bytes as possible. Both
1188 outputs are split into bytes separated by spaces.
1190 If **x** is not an integer, an error message is printed instead, but bc(1)
1191 is not reset (see the **RESET** section).
1193 This is a **void** function (see the *Void Functions* subsection of the
1194 **FUNCTIONS** section).
1198 : Outputs the representation, in binary and hexadecimal, of **x** as an
1199 unsigned integer in **n** bytes. Both outputs are split into bytes separated
1202 If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
1203 error message is printed instead, but bc(1) is not reset (see the **RESET**
1206 This is a **void** function (see the *Void Functions* subsection of the
1207 **FUNCTIONS** section).
1211 : Outputs the representation, in binary and hexadecimal, of **x** as a signed,
1212 two's-complement integer in **n** bytes. Both outputs are split into bytes
1213 separated by spaces.
1215 If **x** is not an integer or cannot fit into **n** bytes, an error message
1216 is printed instead, but bc(1) is not reset (see the **RESET** section).
1218 This is a **void** function (see the *Void Functions* subsection of the
1219 **FUNCTIONS** section).
1223 : Outputs the representation, in binary and hexadecimal, of **x** as an
1224 unsigned integer in **1** byte. Both outputs are split into bytes separated
1227 If **x** is not an integer, is negative, or cannot fit into **1** byte, an
1228 error message is printed instead, but bc(1) is not reset (see the **RESET**
1231 This is a **void** function (see the *Void Functions* subsection of the
1232 **FUNCTIONS** section).
1236 : Outputs the representation, in binary and hexadecimal, of **x** as a signed,
1237 two's-complement integer in **1** byte. Both outputs are split into bytes
1238 separated by spaces.
1240 If **x** is not an integer or cannot fit into **1** byte, an error message
1241 is printed instead, but bc(1) is not reset (see the **RESET** section).
1243 This is a **void** function (see the *Void Functions* subsection of the
1244 **FUNCTIONS** section).
1248 : Outputs the representation, in binary and hexadecimal, of **x** as an
1249 unsigned integer in **2** bytes. Both outputs are split into bytes separated
1252 If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
1253 error message is printed instead, but bc(1) is not reset (see the **RESET**
1256 This is a **void** function (see the *Void Functions* subsection of the
1257 **FUNCTIONS** section).
1261 : Outputs the representation, in binary and hexadecimal, of **x** as a signed,
1262 two's-complement integer in **2** bytes. Both outputs are split into bytes
1263 separated by spaces.
1265 If **x** is not an integer or cannot fit into **2** bytes, an error message
1266 is printed instead, but bc(1) is not reset (see the **RESET** section).
1268 This is a **void** function (see the *Void Functions* subsection of the
1269 **FUNCTIONS** section).
1273 : Outputs the representation, in binary and hexadecimal, of **x** as an
1274 unsigned integer in **4** bytes. Both outputs are split into bytes separated
1277 If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
1278 error message is printed instead, but bc(1) is not reset (see the **RESET**
1281 This is a **void** function (see the *Void Functions* subsection of the
1282 **FUNCTIONS** section).
1286 : Outputs the representation, in binary and hexadecimal, of **x** as a signed,
1287 two's-complement integer in **4** bytes. Both outputs are split into bytes
1288 separated by spaces.
1290 If **x** is not an integer or cannot fit into **4** bytes, an error message
1291 is printed instead, but bc(1) is not reset (see the **RESET** section).
1293 This is a **void** function (see the *Void Functions* subsection of the
1294 **FUNCTIONS** section).
1298 : Outputs the representation, in binary and hexadecimal, of **x** as an
1299 unsigned integer in **8** bytes. Both outputs are split into bytes separated
1302 If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
1303 error message is printed instead, but bc(1) is not reset (see the **RESET**
1306 This is a **void** function (see the *Void Functions* subsection of the
1307 **FUNCTIONS** section).
1311 : Outputs the representation, in binary and hexadecimal, of **x** as a signed,
1312 two's-complement integer in **8** bytes. Both outputs are split into bytes
1313 separated by spaces.
1315 If **x** is not an integer or cannot fit into **8** bytes, an error message
1316 is printed instead, but bc(1) is not reset (see the **RESET** section).
1318 This is a **void** function (see the *Void Functions* subsection of the
1319 **FUNCTIONS** section).
1323 : Outputs the representation of the truncated absolute value of **x** as an
1324 unsigned integer in hexadecimal using **n** bytes. Not all of the value will
1325 be output if **n** is too small.
1327 This is a **void** function (see the *Void Functions* subsection of the
1328 **FUNCTIONS** section).
1330 **binary_uint(x, n)**
1332 : Outputs the representation of the truncated absolute value of **x** as an
1333 unsigned integer in binary using **n** bytes. Not all of the value will be
1334 output if **n** is too small.
1336 This is a **void** function (see the *Void Functions* subsection of the
1337 **FUNCTIONS** section).
1339 **output_uint(x, n)**
1341 : Outputs the representation of the truncated absolute value of **x** as an
1342 unsigned integer in the current **obase** (see the **SYNTAX** section) using
1343 **n** bytes. Not all of the value will be output if **n** is too small.
1345 This is a **void** function (see the *Void Functions* subsection of the
1346 **FUNCTIONS** section).
1348 **output_byte(x, i)**
1350 : Outputs byte **i** of the truncated absolute value of **x**, where **0** is
1351 the least significant byte and **number_of_bytes - 1** is the most
1354 This is a **void** function (see the *Void Functions* subsection of the
1355 **FUNCTIONS** section).
1357 ## Transcendental Functions
1359 All transcendental functions can return slightly inaccurate results (up to 1
1360 [ULP][4]). This is unavoidable, and [this article][5] explains why it is
1361 impossible and unnecessary to calculate exact results for the transcendental
1364 Because of the possible inaccuracy, I recommend that users call those functions
1365 with the precision (**scale**) set to at least 1 higher than is necessary. If
1366 exact results are *absolutely* required, users can double the precision
1367 (**scale**) and then truncate.
1369 The transcendental functions in the standard math library are:
1378 The transcendental functions in the extended math library are:
1396 When bc(1) encounters an error or a signal that it has a non-default handler
1397 for, it resets. This means that several things happen.
1399 First, any functions that are executing are stopped and popped off the stack.
1400 The behavior is not unlike that of exceptions in programming languages. Then
1401 the execution point is set so that any code waiting to execute (after all
1402 functions returned) is skipped.
1404 Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
1405 Then, if it is interactive mode, and the error was not a fatal error (see the
1406 **EXIT STATUS** section), it asks for more input; otherwise, it exits with the
1407 appropriate return code.
1409 Note that this reset behavior is different from the GNU bc(1), which attempts to
1410 start executing the statement right after the one that caused an error.
1414 Most bc(1) implementations use **char** types to calculate the value of **1**
1415 decimal digit at a time, but that can be slow. This bc(1) does something
1418 It uses large integers to calculate more than **1** decimal digit at a time. If
1419 built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
1420 **64**, then each integer has **9** decimal digits. If built in an environment
1421 where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
1422 value (the number of decimal digits per large integer) is called
1425 The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
1426 the **limits** statement.
1428 In addition, this bc(1) uses an even larger integer for overflow checking. This
1429 integer type depends on the value of **BC_LONG_BIT**, but is always at least
1430 twice as large as the integer type used to store digits.
1434 The following are the limits on bc(1):
1438 : The number of bits in the **long** type in the environment where bc(1) was
1439 built. This determines how many decimal digits can be stored in a single
1440 large integer (see the **PERFORMANCE** section).
1444 : The number of decimal digits per large integer (see the **PERFORMANCE**
1445 section). Depends on **BC_LONG_BIT**.
1449 : The max decimal number that each large integer can store (see
1450 **BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
1454 : The max number that the overflow type (see the **PERFORMANCE** section) can
1455 hold. Depends on **BC_LONG_BIT**.
1459 : The maximum output base. Set at **BC_BASE_POW**.
1463 : The maximum size of arrays. Set at **SIZE_MAX-1**.
1467 : The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
1471 : The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
1475 : The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
1479 : The maximum length of a number (in decimal digits), which includes digits
1480 after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
1484 : The maximum integer (inclusive) returned by the **rand()** operand. Set at
1485 **2\^BC_LONG_BIT-1**.
1489 : The maximum allowable exponent (positive or negative). Set at
1490 **BC_OVERFLOW_MAX**.
1494 : The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
1496 The actual values can be queried with the **limits** statement.
1498 These limits are meant to be effectively non-existent; the limits are so large
1499 (at least on 64-bit machines) that there should not be any point at which they
1500 become a problem. In fact, memory should be exhausted before these limits should
1503 # ENVIRONMENT VARIABLES
1505 bc(1) recognizes the following environment variables:
1509 : If this variable exists (no matter the contents), bc(1) behaves as if
1510 the **-s** option was given.
1514 : This is another way to give command-line arguments to bc(1). They should be
1515 in the same format as all other command-line arguments. These are always
1516 processed first, so any files given in **BC_ENV_ARGS** will be processed
1517 before arguments and files given on the command-line. This gives the user
1518 the ability to set up "standard" options and files to be used at every
1519 invocation. The most useful thing for such files to contain would be useful
1520 functions that the user might want every time bc(1) runs.
1522 The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
1523 but it does not understand escape sequences. For example, the string
1524 **"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
1525 **"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
1527 The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
1528 if you have a file with any number of single quotes in the name, you can use
1529 double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
1530 versa if you have a file with double quotes. However, handling a file with
1531 both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
1532 complexity of the parsing, though such files are still supported on the
1533 command-line where the parsing is done by the shell.
1537 : If this environment variable exists and contains an integer that is greater
1538 than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
1539 lines to that length, including the backslash (**\\**). The default line
1544 bc(1) returns the following exit statuses:
1552 : A math error occurred. This follows standard practice of using **1** for
1553 expected errors, since math errors will happen in the process of normal
1556 Math errors include divide by **0**, taking the square root of a negative
1557 number, using a negative number as a bound for the pseudo-random number
1558 generator, attempting to convert a negative number to a hardware integer,
1559 overflow when converting a number to a hardware integer, and attempting to
1560 use a non-integer where an integer is required.
1562 Converting to a hardware integer happens for the second operand of the power
1563 (**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
1564 operators and their corresponding assignment operators.
1568 : A parse error occurred.
1570 Parse errors include unexpected **EOF**, using an invalid character, failing
1571 to find the end of a string or comment, using a token where it is invalid,
1572 giving an invalid expression, giving an invalid print statement, giving an
1573 invalid function definition, attempting to assign to an expression that is
1574 not a named expression (see the *Named Expressions* subsection of the
1575 **SYNTAX** section), giving an invalid **auto** list, having a duplicate
1576 **auto**/function parameter, failing to find the end of a code block,
1577 attempting to return a value from a **void** function, attempting to use a
1578 variable as a reference, and using any extensions when the option **-s** or
1579 any equivalents were given.
1583 : A runtime error occurred.
1585 Runtime errors include assigning an invalid number to **ibase**, **obase**,
1586 or **scale**; give a bad expression to a **read()** call, calling **read()**
1587 inside of a **read()** call, type errors, passing the wrong number of
1588 arguments to functions, attempting to call an undefined function, and
1589 attempting to use a **void** function call as a value in an expression.
1593 : A fatal error occurred.
1595 Fatal errors include memory allocation errors, I/O errors, failing to open
1596 files, attempting to use files that do not have only ASCII characters (bc(1)
1597 only accepts ASCII characters), attempting to open a directory as a file,
1598 and giving invalid command-line options.
1600 The exit status **4** is special; when a fatal error occurs, bc(1) always exits
1601 and returns **4**, no matter what mode bc(1) is in.
1603 The other statuses will only be returned when bc(1) is not in interactive mode
1604 (see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
1605 **RESET** section) and accepts more input when one of those errors occurs in
1606 interactive mode. This is also the case when interactive mode is forced by the
1607 **-i** flag or **-\-interactive** option.
1609 These exit statuses allow bc(1) to be used in shell scripting with error
1610 checking, and its normal behavior can be forced by using the **-i** flag or
1611 **-\-interactive** option.
1615 Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
1616 Interactive mode is turned on automatically when both **stdin** and **stdout**
1617 are hooked to a terminal, but the **-i** flag and **-\-interactive** option can
1618 turn it on in other cases.
1620 In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
1621 section), and in normal execution, flushes **stdout** as soon as execution is
1622 done for the current input.
1626 If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
1629 TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
1630 section). It is also required to enable special handling for **SIGINT** signals.
1632 TTY mode is different from interactive mode because interactive mode is required
1633 in the [bc(1) specification][1], and interactive mode requires only **stdin**
1634 and **stdout** to be connected to a terminal.
1638 Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
1639 bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
1640 **RESET** section). Otherwise, it will clean up and exit.
1642 Note that "current input" can mean one of two things. If bc(1) is processing
1643 input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
1644 processing input from a file in TTY mode, it will stop processing the file and
1645 start processing the next file, if one exists, or ask for input from **stdin**
1646 if no other file exists.
1648 This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
1649 can seem as though bc(1) did not respond to the signal since it will immediately
1650 start executing the next file. This is by design; most files that users execute
1651 when interacting with bc(1) have function definitions, which are quick to parse.
1652 If a file takes a long time to execute, there may be a bug in that file. The
1653 rest of the files could still be executed without problem, allowing the user to
1656 **SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
1657 default handler for all other signals. The one exception is **SIGHUP**; in that
1658 case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
1661 # COMMAND LINE HISTORY
1663 bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
1664 the **TTY MODE** section), history is enabled. Previous lines can be recalled
1665 and edited with the arrow keys.
1667 **Note**: tabs are converted to 8 spaces.
1675 bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
1676 specification. The flags **-efghiqsvVw**, all long options, and the extensions
1677 noted above are extensions to that specification.
1679 Note that the specification explicitly says that bc(1) only accepts numbers that
1680 use a period (**.**) as a radix point, regardless of the value of
1685 None are known. Report bugs at https://git.yzena.com/gavin/bc.
1689 Gavin D. Howard <gavin@yzena.com> and contributors.
1691 [1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
1692 [2]: https://www.gnu.org/software/bc/
1693 [3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
1694 [4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
1695 [5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
1696 [6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero