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36 .\" @(#)dc.1 8.1 (Berkeley) 6/6/93
47 .Op Fl e Ar expression
52 is an arbitrary precision arithmetic package.
53 The overall structure of
56 a stacking (reverse Polish) calculator i.e.\&
57 numbers are stored on a stack.
58 Adding a number pushes it onto the stack.
59 Arithmetic operations pop arguments off the stack
63 utility, which is a preprocessor for
65 providing infix notation and a C-like syntax
66 which implements functions and reasonable control
67 structures for programs.
68 The options are as follows:
70 .It Fl e Ar expr , Fl Fl expression Ar expr
75 options are specified, they will be processed in the order given.
78 argument is given, execution will stop after processing the expressions
79 given on the command line,
80 otherwise processing will continue with the contents of
82 .It Fl f Ar filename , Fl Fl file Ar filename
83 Process the content of the given file before further calculations are done.
86 options are specified, they will be processed in the order given.
88 Print short usage info.
89 .It Fl V , Fl Fl version
92 Enable extended register mode.
95 to allow more than 256 registers.
98 for a more detailed description.
103 operates on decimal integers,
104 but one may specify an input base, output base,
105 and a number of fractional digits (scale) to be maintained.
106 If an argument is given,
107 input is taken from that file until its end,
108 then from the standard input.
109 Whitespace is ignored, except where it signals the end of a number,
110 end of a line or when a register name is expected.
111 The following constructions are recognized:
112 .Bl -tag -width "number"
114 The value of the number is pushed on the stack.
115 A number is an unbroken string of the digits 0\-9 and letters A\-F.
116 It may be preceded by an underscore
118 to input a negative number.
119 A number may contain a single decimal point.
120 A number may also contain the characters A\-F, with the values 10\-15.
121 .It Cm "+ - / * % ~ ^"
123 top two values on the stack are added
130 divided and remaindered (~),
131 or exponentiated (^).
132 The two entries are popped off the stack;
133 the result is pushed on the stack in their place.
134 Any fractional part of an exponent is ignored.
136 For addition and subtraction, the scale of the result is the maximum
137 of scales of the operands.
138 For division the scale of the result is defined
139 by the scale set by the
142 For multiplication, the scale is defined by the expression
143 .Sy min(a+b,max(a,b,scale)) ,
148 are the scales of the operands, and
150 is the scale defined by the
153 For exponentiation with a non-negative exponent, the scale of the result is
154 .Sy min(a*b,max(scale,a)) ,
157 is the scale of the base, and
162 If the exponent is negative, the scale of the result is the scale
167 In the case of the division and modulus operator (~),
168 the resultant quotient is pushed first followed by the remainder.
169 This is a shorthand for the sequence:
170 .Bd -literal -offset indent -compact
173 The division and modulus operator is a non-portable extension.
175 Pop the top value from the stack.
176 If that value is a number, compute the integer part of the number modulo 256.
177 If the result is zero, push an empty string.
178 Otherwise push a one character string by interpreting the computed value
183 If the top value is a string, push a string containing the first character
184 of the original string.
185 If the original string is empty, an empty string is pushed back.
188 operator is a non-portable extension.
190 All values on the stack are popped.
192 The top value on the stack is duplicated.
194 All values on the stack are printed, separated by newlines.
196 The top two numbers are popped from the stack and compared.
197 A one is pushed if the top of the stack is equal to the second number
199 A zero is pushed otherwise.
200 This is a non-portable extension.
202 Pushes the input base on the top of the stack.
204 The top value on the stack is popped and used as the
205 base for further input.
206 The initial input base is 10.
208 Pop the top value from the stack.
209 The recursion level is popped by that value and, following that,
210 the input is skipped until the first occurrence of the
215 operator is a non-portable extension, used by the
219 The current scale factor is pushed onto the stack.
221 The top of the stack is popped, and that value is used as
222 a non-negative scale factor:
223 the appropriate number of places
224 are printed on output,
225 and maintained during multiplication, division, and exponentiation.
226 The interaction of scale factor,
227 input base, and output base will be reasonable if all are changed
232 is treated as a stack and its top value is popped onto the main stack.
237 is pushed on the stack.
241 Initially, all registers contain the value zero.
248 operator is a non-portable extensions, used by the
252 The top of the stack is replaced by one if the top of the stack
254 If the top of the stack is unequal to zero, it is replaced by zero.
255 This is a non-portable extension.
257 The top value on the stack is popped and printed without a newline.
258 This is a non-portable extension.
260 Pushes the output base on the top of the stack.
262 The top value on the stack is popped and used as the
263 base for further output.
264 The initial output base is 10.
266 The top of the stack is popped.
267 If the top of the stack is a string, it is printed without a trailing newline.
268 If the top of the stack is a number, it is interpreted as a
269 base 256 number, and each digit of this base 256 number is printed as
272 character, without a trailing newline.
274 The top value on the stack is printed with a trailing newline.
275 The top value remains unchanged.
277 The top value on the stack is popped and the string execution level is popped
281 If executing a string, the recursion level is
284 The top of the stack is removed (popped).
285 This is a non-portable extension.
287 The top two values on the stack are reversed (swapped).
288 This is a non-portable extension.
292 is treated as a stack.
293 The top value of the main stack is popped and pushed on it.
296 top of the stack is popped and stored into
300 Replaces the top element on the stack by its square root.
301 The scale of the result is the maximum of the scale of the argument
302 and the current value of scale.
304 Replaces the number on the top of the stack with its scale factor.
305 If the top of the stack is a string, replace it with the integer 0.
307 Treats the top element of the stack as a character string
308 and executes it as a string of
312 Replaces the number on the top of the stack with its length.
313 The length of a string is its number of characters.
314 The length of a number is its number of digits, not counting the minus sign
317 The stack level is pushed onto the stack.
318 .It Cm \&[ Ns ... Ns Cm \&]
321 string onto the top of the stack.
322 If the string includes brackets, these must be properly balanced.
323 The backslash character
325 may be used as an escape character, making it
326 possible to include unbalanced brackets in strings.
327 To include a backslash in a string, use a double backslash.
336 The top two elements of the stack are popped and compared.
339 is executed if they obey the stated
342 .Cm < Ns Va x Ns e Ns Va y
343 .Cm > Ns Va x Ns e Ns Va y
344 .Cm = Ns Va x Ns e Ns Va y
345 .Cm !< Ns Va x Ns e Ns Va y
346 .Cm !> Ns Va x Ns e Ns Va y
347 .Cm != Ns Va x Ns e Ns Va y
349 These operations are variants of the comparison operations above.
350 The first register name is followed by the letter
352 and another register name.
355 will be executed if the relation is true, and register
357 will be executed if the relation is false.
358 This is a non-portable extension.
360 The top two numbers are popped from the stack and compared.
361 A one is pushed if the top of the stack is less than the second number
363 A zero is pushed otherwise.
364 This is a non-portable extension.
366 The top two numbers are popped from the stack and compared.
367 A one is pushed if the top of stack is less than or equal to the
368 second number on the stack.
369 A zero is pushed otherwise.
370 This is a non-portable extension.
372 Interprets the rest of the line as a
376 A line of input is taken from the input source (usually the terminal)
379 Pop two values from the stack.
380 The second value on the stack is stored into the array
382 indexed by the top of stack.
384 Pop a value from the stack.
385 The value is used as an index into register
387 The value in this register is pushed onto the stack.
389 Array elements initially have the value zero.
390 Each level of a stacked register has its own array associated with
393 .Bd -literal -offset indent
394 [first] 0:a [dummy] Sa [second] 0:a 0;a p La 0;a p
398 .Bd -literal -offset indent
405 is written in an array that is later popped, to reveal the array that
409 Skip the rest of the line.
410 This is a non-portable extension.
413 Registers have a single character name
417 may be any character, including space, tab or any other special character.
418 If extended register mode is enabled using the
420 option and the register identifier
422 has the value 255, the next two characters are interpreted as a
423 two-byte register index.
424 The set of standard single character registers and the set of extended
425 registers do not overlap.
426 Extended register mode is a non-portable extension.
428 An example which prints the first ten values of
430 .Bd -literal -offset indent
436 Independent of the current input base, the command
437 .Bd -literal -offset indent
441 will reset the input base to decimal 10.
444 .It %c (0%o) is unimplemented
445 an undefined operation was called.
447 for not enough elements on the stack to do what was asked.
448 .It stack register '%c' (0%o) is empty
451 operation from a stack register that is empty.
452 .It Runtime warning: non-zero scale in exponent
453 for a fractional part of an exponent that is being ignored.
455 for trying to divide by zero.
456 .It remainder by zero
457 for trying to take a remainder by zero.
458 .It square root of negative number
459 for trying to take the square root of a negative number.
461 for an array index that is larger than 2048.
463 for a negative array index.
464 .It "input base must be a number between 2 and 16"
465 for trying to set an illegal input base.
466 .It output base must be a number greater than 1
467 for trying to set an illegal output base.
468 .It scale must be a nonnegative number
469 for trying to set a negative or zero scale.
471 for trying to set a scale that is too large.
472 A scale must be representable as a 32-bit unsigned number.
473 .It Q command argument exceeded string execution depth
474 for trying to pop the recursion level more than the current
476 .It Q command requires a number >= 1
477 for trying to pop an illegal number of recursion levels.
478 .It recursion too deep
479 for too many levels of nested execution.
481 The recursion level is increased by one if the
485 operation or one of the compare operations resulting in the execution
486 of register is executed.
487 As an exception, the recursion level is not increased if the operation
488 is executed as the last command of a string.
489 For example, the commands
490 .Bd -literal -offset indent
495 will execute an endless loop, while the commands
496 .Bd -literal -offset indent
501 will terminate because of a too deep recursion level.
502 .It J command argument exceeded string execution depth
503 for trying to pop the recursion level more than the current
506 for a failed scan for an occurrence of the
516 "DC \- An Interactive Desk Calculator"
517 .Pa /usr/share/doc/usd/05.dc/ .
519 The arithmetic operations of the
521 utility are expected to conform to the definition listed in the
529 command first appeared in
531 A complete rewrite of the
535 big number routines first appeared in
539 The original version of the
541 command was written by
545 The current version of the
547 utility was written by