1.\" $OpenBSD: dc.1,v 1.19 2004/10/18 07:49:00 otto Exp $ 2.\" 3.\" Copyright (C) Caldera International Inc. 2001-2002. 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code and documentation must retain the above 10.\" copyright notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed or owned by Caldera 17.\" International, Inc. 18.\" 4. Neither the name of Caldera International, Inc. nor the names of other 19.\" contributors may be used to endorse or promote products derived from 20.\" this software without specific prior written permission. 21.\" 22.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA 23.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR 24.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26.\" IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT, 27.\" INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 28.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 29.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 31.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING 32.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 33.\" POSSIBILITY OF SUCH DAMAGE. 34.\" 35.\" @(#)dc.1 8.1 (Berkeley) 6/6/93 36.\" 37.Dd October 10, 2004 38.Dt DC 1 39.Os 40.Sh NAME 41.Nm dc 42.Nd desk calculator 43.Sh SYNOPSIS 44.Nm 45.Op Fl x 46.Op Fl e Ar expression 47.Op Ar file 48.Sh DESCRIPTION 49.Nm 50is an arbitrary precision arithmetic package. 51The overall structure of 52.Nm 53is 54a stacking (reverse Polish) calculator i.e.\& 55numbers are stored on a stack. 56Adding a number pushes it onto the stack. 57Arithmetic operations pop arguments off the stack 58and push the results. 59See also the 60.Xr bc 1 61utility, which is a preprocessor for 62.Nm 63providing infix notation and a C-like syntax 64which implements functions and reasonable control 65structures for programs. 66The options are as follows: 67.Bl -tag -width Ds 68.It Fl e Ar expression 69Evaluate 70.Ar expression . 71If multiple 72.Fl e 73options are specified, they will be processed in the order given. 74If no 75.Ar file 76argument is given, execution will stop after processing the expressions 77given on the command line, 78otherwise processing will continue with the contents of 79.Ar file . 80.It Fl x 81Enable extended register mode. 82This mode is used by 83.Xr bc 1 84to allow more than 256 registers. 85See 86.Sx Registers 87for a more detailed description. 88.El 89.Pp 90Ordinarily, 91.Nm 92operates on decimal integers, 93but one may specify an input base, output base, 94and a number of fractional digits (scale) to be maintained. 95If an argument is given, 96input is taken from that file until its end, 97then from the standard input. 98Whitespace is ignored, expect where it signals the end of a number, 99end of a line or when a register name is expected. 100The following constructions are recognized: 101.Bl -tag -width "number" 102.It Va number 103The value of the number is pushed on the stack. 104A number is an unbroken string of the digits 0\-9 and letters A\-F. 105It may be preceded by an underscore 106.Pq Sq _ 107to input a negative number. 108A number may contain a single decimal point. 109A number may also contain the characters A\-F, with the values 10\-15. 110.It Cm "+ - / * % ~ ^" 111The 112top two values on the stack are added 113(+), 114subtracted 115(\-), 116multiplied (*), 117divided (/), 118remaindered (%), 119divided and remaindered (~), 120or exponentiated (^). 121The two entries are popped off the stack; 122the result is pushed on the stack in their place. 123Any fractional part of an exponent is ignored. 124.Pp 125For addition and subtraction, the scale of the result is the maximum 126of scales of the operands. 127For division the scale of the result is defined 128by the scale set by the 129.Ic k 130operation. 131For multiplication, the scale is defined by the expression 132.Sy min(a+b,max(a,b,scale)) , 133where 134.Sy a 135and 136.Sy b 137are the scales of the operands, and 138.Sy scale 139is the scale defined by the 140.Ic k 141operation. 142For exponentiation with a non-negative exponent, the scale of the result is 143.Sy min(a*b,max(scale,a)) , 144where 145.Sy a 146is the scale of the base, and 147.Sy b 148is the 149.Em value 150of the exponent. 151If the exponent is negative, the scale of the result is the scale 152defined by the 153.Ic k 154operation. 155.Pp 156In the case of the division and modulus operator (~), 157the resultant quotient is pushed first followed by the remainder. 158This is a shorthand for the sequence: 159.Bd -literal -offset indent -compact 160x y / x y % 161.Ed 162The division and modulus operator is a non-portable extension. 163.It Ic a 164Pop the top value from the stack. 165If that value is a number, compute the integer part of the number modulo 256. 166If the result is zero, push an empty string. 167Otherwise push a one character string by interpreting the computed value 168as an 169.Tn ASCII 170character. 171.Pp 172If the top value is a string, push a string containing the first character 173of the original string. 174If the original string is empty, an empty string is pushed back. 175The 176.Ic a 177operator is a non-portable extension. 178.It Ic c 179All values on the stack are popped. 180.It Ic d 181The top value on the stack is duplicated. 182.It Ic f 183All values on the stack are printed, separated by newlines. 184.It Ic G 185The top two numbers are popped from the stack and compared. 186A one is pushed if the top of the stack is equal to the second number 187on the stack. 188A zero is pushed otherwise. 189This is a non-portable extension. 190.It Ic i 191The top value on the stack is popped and used as the 192base for further input. 193The initial input base is 10. 194.It Ic I 195Pushes the input base on the top of the stack. 196.It Ic J 197Pop the top value from the stack. 198The recursion level is popped by that value and, following that, 199the input is skipped until the first occurrence of the 200.Ic M 201operator. 202The 203.Ic J 204operator is a non-portable extension, used by the 205.Xr bc 1 206command. 207.It Ic K 208The current scale factor is pushed onto the stack. 209.It Ic k 210The top of the stack is popped, and that value is used as 211a non-negative scale factor: 212the appropriate number of places 213are printed on output, 214and maintained during multiplication, division, and exponentiation. 215The interaction of scale factor, 216input base, and output base will be reasonable if all are changed 217together. 218.It Ic L Ns Ar x 219Register 220.Ar x 221is treated as a stack and its top value is popped onto the main stack. 222.It Ic l Ns Ar x 223The 224value in register 225.Ar x 226is pushed on the stack. 227The register 228.Ar x 229is not altered. 230Initially, all registers contain the value zero. 231.It Ic M 232Mark used by the 233.Ic J 234operator. 235The 236.Ic M 237operator is a non-portable extensions, used by the 238.Xr bc 1 239command. 240.It Ic N 241The top of the stack is replaced by one if the top of the stack 242is equal to zero. 243If the top of the stack is unequal to zero, it is replaced by zero. 244This is a non-portable extension. 245.It Ic n 246The top value on the stack is popped and printed without a newline. 247This is a non-portable extension. 248.It Ic O 249Pushes the output base on the top of the stack. 250.It Ic o 251The top value on the stack is popped and used as the 252base for further output. 253The initial output base is 10. 254.It Ic P 255The top of the stack is popped. 256If the top of the stack is a string, it is printed without a trailing newline. 257If the top of the stack is a number, it is interpreted as a 258base 256 number, and each digit of this base 256 number is printed as 259an 260.Tn ASCII 261character, without a trailing newline. 262.It Ic p 263The top value on the stack is printed with a trailing newline. 264The top value remains unchanged. 265.It Ic Q 266The top value on the stack is popped and the string execution level is popped 267by that value. 268.It Ic q 269Exits the program. 270If executing a string, the recursion level is 271popped by two. 272.It Ic R 273The top of the stack is removed (popped). 274This is a non-portable extension. 275.It Ic r 276The top two values on the stack are reversed (swapped). 277This is a non-portable extension. 278.It Ic S Ns Ar x 279Register 280.Ar x 281is treated as a stack. 282The top value of the main stack is popped and pushed on it. 283.It Ic s Ns Ar x 284The 285top of the stack is popped and stored into 286a register named 287.Ar x . 288.It Ic v 289Replaces the top element on the stack by its square root. 290The scale of the result is the maximum of the scale of the argument 291and the current value of scale. 292.It Ic X 293Replaces the number on the top of the stack with its scale factor. 294If the top of the stack is a string, replace it with the integer 0. 295.It Ic x 296Treats the top element of the stack as a character string 297and executes it as a string of 298.Nm 299commands. 300.It Ic Z 301Replaces the number on the top of the stack with its length. 302The length of a string is its number of characters. 303The length of a number is its number of digits, not counting the minus sign 304and decimal point. 305.It Ic z 306The stack level is pushed onto the stack. 307.It Cm \&[ Ns ... Ns Cm \&] 308Puts the bracketed 309.Tn ASCII 310string onto the top of the stack. 311If the string includes brackets, these must be properly balanced. 312The backslash character 313.Pq Sq \e 314may be used as an escape character, making it 315possible to include unbalanced brackets in strings. 316To include a backslash in a string, use a double backslash. 317.It Xo 318.Cm < Ns Va x 319.Cm > Ns Va x 320.Cm = Ns Va x 321.Cm !< Ns Va x 322.Cm !> Ns Va x 323.Cm != Ns Va x 324.Xc 325The top two elements of the stack are popped and compared. 326Register 327.Ar x 328is executed if they obey the stated 329relation. 330.It Xo 331.Cm < Ns Va x Ns e Ns Va y 332.Cm > Ns Va x Ns e Ns Va y 333.Cm = Ns Va x Ns e Ns Va y 334.Cm !< Ns Va x Ns e Ns Va y 335.Cm !> Ns Va x Ns e Ns Va y 336.Cm != Ns Va x Ns e Ns Va y 337.Xc 338These operations are variants of the comparison operations above. 339The first register name is followed by the letter 340.Sq e 341and another register name. 342Register 343.Ar x 344will be executed if the relation is true, and register 345.Ar y 346will be executed if the relation is false. 347This is a non-portable extension. 348.It Ic \&( 349The top two numbers are popped from the stack and compared. 350A one is pushed if the top of the stack is less than the second number 351on the stack. 352A zero is pushed otherwise. 353This is a non-portable extension. 354.It Ic { 355The top two numbers are popped from the stack and compared. 356A one is pushed if the top of stack is less than or equal to the 357second number on the stack. 358A zero is pushed otherwise. 359This is a non-portable extension. 360.It Ic \&! 361Interprets the rest of the line as a 362.Ux 363command. 364.It Ic \&? 365A line of input is taken from the input source (usually the terminal) 366and executed. 367.It Ic \&: Ns Ar r 368Pop two values from the stack. 369The second value on the stack is stored into the array 370.Ar r 371indexed by the top of stack. 372.It Ic \&; Ns Ar r 373Pop a value from the stack. 374The value is used as an index into register 375.Ar r . 376The value in this register is pushed onto the stack. 377.Pp 378Array elements initially have the value zero. 379Each level of a stacked register has its own array associated with 380it. 381The command sequence 382.Bd -literal -offset indent 383[first] 0:a [dummy] Sa [second] 0:a 0;a p La 0;a p 384.Ed 385.Pp 386will print 387.Bd -literal -offset indent 388second 389first 390.Ed 391.Pp 392since the string 393.Ql second 394is written in an array that is later popped, to reveal the array that 395stored 396.Ql first . 397.It Ic # 398Skip the rest of the line. 399This is a non-portable extension. 400.El 401.Ss Registers 402Registers have a single character name 403.Ar x , 404where 405.Ar x 406may be any character, including space, tab or any other special character. 407If extended register mode is enabled using the 408.Fl x 409option and the register identifier 410.Ar x 411has the value 255, the next two characters are interpreted as a 412two-byte register index. 413The set of standard single character registers and the set of extended 414registers do not overlap. 415Extended register mode is a non-portable extension. 416.Sh EXAMPLES 417An example which prints the first ten values of 418.Ic n! : 419.Bd -literal -offset indent 420[la1+dsa*pla10>y]sy 4210sa1 422lyx 423.Ed 424.Pp 425Independent of the current input base, the command 426.Bd -literal -offset indent 427Ai 428.Ed 429.Pp 430will reset the input base to decimal 10. 431.Sh DIAGNOSTICS 432.Bl -diag 433.It %c (0%o) is unimplemented 434an undefined operation was called. 435.It stack empty 436for not enough elements on the stack to do what was asked. 437.It stack register '%c' (0%o) is empty 438for an 439.Ar L 440operation from a stack register that is empty. 441.It Runtime warning: non-zero scale in exponent 442for a fractional part of an exponent that is being ignored. 443.It divide by zero 444for trying to divide by zero. 445.It remainder by zero 446for trying to take a remainder by zero. 447.It square root of negative number 448for trying to take the square root of a negative number. 449.It index too big 450for an array index that is larger than 2048. 451.It negative index 452for a negative array index. 453.It "input base must be a number between 2 and 16" 454for trying to set an illegal input base. 455.It output base must be a number greater than 1 456for trying to set an illegal output base. 457.It scale must be a nonnegative number 458for trying to set a negative or zero scale. 459.It scale too large 460for trying to set a scale that is too large. 461A scale must be representable as a 32-bit unsigned number. 462.It Q command argument exceeded string execution depth 463for trying to pop the recursion level more than the current 464recursion level. 465.It Q command requires a number >= 1 466for trying to pop an illegal number of recursion levels. 467.It recursion too deep 468for too many levels of nested execution. 469.Pp 470The recursion level is increased by one if the 471.Ar x 472or 473.Ar ?\& 474operation or one of the compare operations resulting in the execution 475of register is executed. 476As an exception, the recursion level is not increased if the operation 477is executed as the last command of a string. 478For example, the commands 479.Bd -literal -offset indent 480[lax]sa 4811 lax 482.Ed 483.Pp 484will execute an endless loop, while the commands 485.Bd -literal -offset indent 486[laxp]sa 4871 lax 488.Ed 489.Pp 490will terminate because of a too deep recursion level. 491.It J command argument exceeded string execution depth 492for trying to pop the recursion level more than the current 493recursion level. 494.It mark not found 495for a failed scan for an occurrence of the 496.Ic M 497operator. 498.El 499.Sh SEE ALSO 500.Xr bc 1 501.Rs 502.%B USD:05 503.%A L. L. Cherry 504.%A R. Morris 505.%T "DC \- An Interactive Desk Calculator" 506.Re 507.Sh STANDARDS 508The arithmetic operations of the 509.Nm 510utility are expected to conform to the definition listed in the 511.Xr bc 1 512section of the 513.St -p1003.2 514specification. 515.Sh HISTORY 516The 517.Nm 518command first appeared in 519.At v6 . 520A complete rewrite of the 521.Nm 522command using the 523.Xr bn 3 524big number routines first appeared in 525.Ox 3.5 . 526.Sh AUTHORS 527.An -nosplit 528The original version of the 529.Nm 530command was written by 531.An Robert Morris 532and 533.An Lorinda Cherry . 534The current version of the 535.Nm 536utility was written by 537.An Otto Moerbeek . 538