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36 .\" @(#)bc.1 6.8 (Berkeley) 8/8/91
43 .Nd arbitrary-precision arithmetic language and calculator
47 .Op Fl e Ar expression
51 is an interactive processor for a language which resembles
52 C but provides unlimited precision arithmetic.
53 It takes input from any expressions on the command line and
54 any files given, then reads the standard input.
60 is actually a preprocessor for
62 which it invokes automatically, unless the
66 In this case the generated
68 instructions are sent to the standard output,
69 instead of being interpreted by a running
72 .It Fl e Ar expression , Fl Fl expression Ar expression
77 options are specified, they are processed in the order given,
78 separated by newlines.
80 Prints usage information.
81 .It Fl l , Fl Fl mathlib
82 Allow specification of an arbitrary precision math library.
83 The definitions in the library are available to command line
85 .It Fl v , Fl Fl version
86 Prints version information.
91 programs is as follows:
98 As a non-portable extension, it is possible to use long names
99 in addition to single letter names.
100 A long name is a sequence starting with a lowercase letter
101 followed by any number of lowercase letters and digits.
102 The underscore character
107 .Bd -unfilled -offset indent -compact
108 are enclosed in /* and */
109 are enclosed in # and the next newline
112 The newline is not part of the line comment,
113 which in itself is a non-portable extension.
116 .Bd -unfilled -offset indent -compact
118 array elements: L [ E ]
119 The words `ibase', `obase', and `scale'
120 The word `last' or a single dot
124 .Bd -unfilled -offset indent -compact
125 arbitrarily long numbers with optional sign and decimal point
128 length ( E ) number of significant decimal digits
129 scale ( E ) number of digits right of decimal point
134 .Sq \e<newline><whitespace>
135 is ignored within numbers.
139 The following arithmetic and logical operators can be used.
140 The semantics of the operators is the same as in the C language.
141 They are listed in order of decreasing precedence.
142 Operators in the same group have the same precedence.
143 .Bl -column -offset indent "= += \-= *= /= %= ^=" "Associativity" \
144 "multiply, divide, modulus"
145 .It Sy "Operator" Ta Sy "Associativity" Ta Sy "Description"
146 .It "++ \-\-" Ta "none" Ta "increment, decrement"
147 .It "\-" Ta "none" Ta "unary minus"
148 .It "^" Ta "right" Ta "power"
149 .It "* / %" Ta "left" Ta "multiply, divide, modulus"
150 .It "+ \-" Ta "left" Ta "plus, minus"
151 .It "= += -= *= /= %= ^=" Ta "right" Ta "assignment"
152 .It "== <= >= != < >" Ta "none" Ta "relational"
153 .It "!" Ta "none" Ta "boolean not"
154 .It "&&" Ta "left" Ta "boolean and"
155 .It "||" Ta "left" Ta "boolean or"
159 .Bl -bullet -offset indent
161 The relational operators may appear in any expression.
164 standard only allows them in the conditional expression of an
171 The relational operators have a lower precedence than the assignment
173 This has the consequence that the expression
177 which is probably not what the programmer intended.
179 In contrast with the C language, the relational operators all have
180 the same precedence, and are non-associative.
183 will produce a syntax error.
185 The boolean operators (!, && and ||) are non-portable extensions.
188 (!) operator has much lower precedence than the same operator in the
190 This has the consequence that the expression
194 Prudent programmers use parentheses when writing expressions involving
199 .Bd -unfilled -offset indent -compact
210 a string of characters, enclosed in double quotes
214 A string may contain any character, except double quote.
215 The if statement with an else branch is a non-portable extension.
216 All three E's in a for statement may be empty.
217 This is a non-portable extension.
218 The continue and print statements are also non-portable extensions.
220 The print statement takes a list of comma-separated expressions.
221 Each expression in the list is evaluated and the computed
222 value is printed and assigned to the variable `last'.
223 No trailing newline is printed.
224 The expression may also be a string enclosed in double quotes.
225 Within these strings the following escape sequences may be used:
242 Any other character following a backslash will be ignored.
243 Strings will not be assigned to `last'.
246 .Bd -unfilled -offset indent
247 define L ( L ,..., L ) {
254 As a non-portable extension, the opening brace of the define statement
255 may appear on the next line.
256 The return statement may also appear in the following forms:
257 .Bd -unfilled -offset indent
263 The first two are equivalent to the statement
265 The last form is a non-portable extension.
266 Not specifying a return statement is equivalent to writing
269 Functions available in the math library, which is loaded by specifying the
271 flag on the command line
273 .Bl -tag -width j(n,x) -offset indent -compact
288 All function arguments are passed by value.
290 The value of a statement that is an expression is printed
291 unless the main operator is an assignment.
292 The value printed is assigned to the special variable `last'.
293 This is a non-portable extension.
294 A single dot may be used as a synonym for `last'.
295 Either semicolons or newlines may separate statements.
298 influences the number of digits to be retained on arithmetic
299 operations in the manner of
305 set the input and output number radix respectively.
307 The same letter may be used as an array, a function,
308 and a simple variable simultaneously.
309 All variables are global to the program.
310 `Auto' variables are pushed down during function calls.
311 When using arrays as function arguments
312 or defining them as automatic variables,
313 empty square brackets must follow the array name.
316 .Bd -literal -offset indent
333 defines a function to compute an approximate value of
334 the exponential function and
336 .Dl for(i=1; i<=10; i++) e(i)
338 prints approximate values of the exponential function of
339 the first ten integers.
340 .Bd -literal -offset indent
341 $ bc -l -e 'scale = 500; 2 * a(2^10000)' -e quit
344 prints an approximation of pi.
346 .Bl -tag -width /usr/share/misc/bc.library -compact
347 .It Pa /usr/share/misc/bc.library
348 math library, read when the
350 option is specified on the command line.
357 options are no-ops for compatibility with some other implementations of
359 and their use is discouraged.
363 "BC \- An Arbitrary Precision Desk-Calculator Language",
364 .Pa /usr/share/doc/usd/06.bc/ .
368 utility is compliant with the
374 are extensions to that specification.
378 command first appeared in
380 A complete rewrite of the
382 command first appeared in
386 The original version of the
388 command was written by
392 The current version of the
394 utility was written by
398 is interpreted when read, not when executed.
400 Some non-portable extensions, as found in the GNU version of the
402 utility are not implemented (yet).