.\" $OpenBSD: dc.1,v 1.4 2003/09/22 14:50:32 otto Exp $ .\" .\" Copyright (C) Caldera International Inc. 2001-2002. .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code and documentation must retain the above .\" copyright notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed or owned by Caldera .\" International, Inc. .\" 4. Neither the name of Caldera International, Inc. nor the names of other .\" contributors may be used to endorse or promote products derived from .\" this software without specific prior written permission. .\" .\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA .\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT, .\" INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES .\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR .\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING .\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE .\" POSSIBILITY OF SUCH DAMAGE. .\" .\" @(#)dc.1 8.1 (Berkeley) 6/6/93 .\" .Dd June 6, 1993 .Dt DC 1 .Sh NAME .Nm dc .Nd desk calculator .Sh SYNOPSIS .Nm .Op Ar file .Sh DESCRIPTION .Nm is an arbitrary precision arithmetic package. The overall structure of .Nm is a stacking (reverse Polish) calculator i.e.\& numbers are stored on a stack. Adding a number pushes it onto the stack. Arithmetic operations pop arguments off the stack and push the results. See also the .Xr bc 1 utility, which is a preprocessor for .Nm providing infix notation and a C-like syntax which implements functions and reasonable control structures for programs. .Pp Ordinarily, .Nm operates on decimal integers, but one may specify an input base, output base, and a number of fractional digits (scale) to be maintained. If an argument is given, input is taken from that file until its end, then from the standard input. Whitespace is ignored, expect where it signals the end of a number, end of a line or when a register name is expected. The following constructions are recognized: .Bl -tag -width "number" .It Va number The value of the number is pushed on the stack. A number is an unbroken string of the digits 0\-9 and letters A\-F. It may be preceded by an underscore .Pq Sq _ to input a negative number. A number may contain a single decimal point. A number may also contain the characters A\-F, with the values 10\-15. .It Cm "+ - / * % ^" The top two values on the stack are added (+), subtracted (\-), multiplied (*), divided (/), remaindered (%), or exponentiated (^). The two entries are popped off the stack; the result is pushed on the stack in their place. Any fractional part of an exponent is ignored. .Pp For addition and subtraction, the scale of the result is the maximum of scales of the operands. For division the scale of the result is defined by the scale set by the .Ar k operation. For multiplication, the scale is defined by the expression .Sy min(a+b,max(a,b,scale)) , where .Sy a and .Sy b are the scales of the operands, and .Sy scale is the scale defined by the .Ar k operation. For exponentation with a non-negative exponent, the scale of the result is .Sy min(a*b,max(scale,a)) , where .Sy a is the scale of the base, and .Sy b is the .Em value of the exponent. If the exponent is negative, the scale of the result is the scale defined by the .Ar k operation. .It Ic s Ns Ar x The top of the stack is popped and stored into a register named .Ar x , where .Ar x may be any character, including space, tab or any other special character. If the .Ar s is capitalized, .Ar x is treated as a stack and the value is pushed on it. .It Ic l Ns Ar x The value in register .Ar x is pushed on the stack. The register .Ar x is not altered. Initially, all registers contain the value zero. If the .Ar l is capitalized, register .Ar x is treated as a stack and its top value is popped onto the main stack. .It Ic d The top value on the stack is duplicated. .It Ic p The top value on the stack is printed with a trailing newline. The top value remains unchanged. .It Ic P The top of the stack is popped. If the top of the stack is a string, it is printed without a trailing newline. If the top of the stack is a number, it is interpreted as a base 256 number, and each digit of this base 256 number is printed as an .Tn ASCII character, without a trailing newline. .It Ic f All values on the stack are printed, separated by newlines. .It Ic q Exits the program. If executing a string, the recursion level is popped by two. If .Ar q is capitalized, the top value on the stack is popped and the string execution level is popped by that value. .It Ic x Treats the top element of the stack as a character string and executes it as a string of .Nm commands. .It Ic X Replaces the number on the top of the stack with its scale factor. If the top of the stack is a string, replace it with the integer 0. .It Cm [ Ns ... Ns Cm ] Puts the bracketed .Tn ASCII string onto the top of the stack. The brackets may be nested. .It Xo .Cm < Ns Va x .Cm > Ns Va x .Cm = Ns Va x .Cm !< Ns Va x .Cm !> Ns Va x .Cm != Ns Va x .Xc The top two elements of the stack are popped and compared. Register .Ar x is executed if they obey the stated relation. .It Ic v Replaces the top element on the stack by its square root. The scale of the result is the maximum of the scale of the argument and the current value of scale. .It Ic \&! Interprets the rest of the line as a .Ux command. .It Ic c All values on the stack are popped. .It Ic i The top value on the stack is popped and used as the base for further input. The initial input base is 10. .Ic I Pushes the input base on the top of the stack. .It Ic o The top value on the stack is popped and used as the base for further output. The initial output base is 10. .It Ic O Pushes the output base on the top of the stack. .It Ic k The top of the stack is popped, and that value is used as a non-negative scale factor: the appropriate number of places are printed on output, and maintained during multiplication, division, and exponentiation. The interaction of scale factor, input base, and output base will be reasonable if all are changed together. .It Ic K The current scale factor is pushed onto the stack. .It Ic z The stack level is pushed onto the stack. .It Ic Z Replaces the number on the top of the stack with its length. The length of a string is its number of characters. The length of a number is its number of digits, not counting the minus sign and decimal point. .It Ic \&? A line of input is taken from the input source (usually the terminal) and executed. .It Ic : Ns Ar r Pop two values from the stack. The second value on the stack is stored into the array .Ar r indexed by the top of stack. .It Ic ; Ns Ar r Pop a value from the stack. The value is used as an index into register .Ar r . The value in this register is pushed onto the stack. .Pp Array elements initially have the value zero. Each level of a stacked register has its own array associated with it. The command sequence .Bd -literal -offset indent [first] 0:a [dummy] Sa [second] 0:a 0;a p La 0;a p .Ed .Pp will print .Bd -literal -offset indent second first .Ed .Pp since the string .Ql second is written in an array that is later popped, to reveal the array that stored .Ql first . .El .Sh EXAMPLES An example which prints the first ten values of .Ic n! : .Bd -literal -offset indent [la1+dsa*pla10>y]sy 0sa1 lyx .Ed .Pp Independent of the current input base, the command .Bd -literal -offset indent Ai .Ed .Pp will reset the input base to decimal 10. .Sh DIAGNOSTICS .Bl -diag .It %c (0%o) is unimplemented an undefined operation was called. .It stack empty for not enough elements on the stack to do what was asked. .It stack register '%c' (0%o) is empty for an .Ar L operation from a stack register that is empty. .It Runtime warning: non-zero scale in exponent for a fractional part of an exponent that is being ignored. .It divide by zero for trying to divide by zero. .It remainder by zero for trying to take a remainder by zero. .It square root of negative number for trying to take the square root of a negative number. .It index too big for an array index that is larger than 2048. .It negative index for a negative array index. .It input base must be a number between 2 and 16 for trying to set an illegal input base. .It output base must be a number greater than 1 for trying to set an illegal input base. .It scale must be a nonnegative number for trying to set a negative or zero scale. .It scale too large for trying to set a scale that is too large. A scale must be representable as a 32-bit unsigned number. .It Q command argument exceeded string execution depth for trying to pop the recursion level more than the current recursion level. .It Q command requires a number >= 1 for trying to pop an illegal number of recursion levels. .It recursion too deep for too many levels of nested execution. .Pp The recursion level is increased by one if the .Ar x or .Ar ?\& operation or one of the compare operations resulting in the execution of register is executed. As an exception, the recursion level is not increased if the operation is executed as the last command of a string. For example, the commands .Bd -literal -offset indent [lax]sa 1 lax .Ed .Pp will execute an endless loop, while the commands .Bd -literal -offset indent [laxp]sa 1 lax .Ed .Pp will terminate because of a too deep recursion level. .El .Sh SEE ALSO .Xr bc 1 .Pp USD:05 .Em "DC \- An Interactive Desk Calculator" .Sh STANDARDS The arithmetic operations of the .Nm utility are expected to conform to the definition listed in the .Xr bc 1 section of the .St -p1003.2 specification. .Sh HISTORY The .Nm command first appeared in .At v6 . A complete rewrite of the .Nm command using the .Xr bn 3 big number routines first appeared in .Ox 3.5 . .Sh AUTHORS The original version of the .Nm command was written by .An Robert Morris and .An Lorinda Cherry . The current version of the .Nm utility was written by .An Otto Moerbeek .