559 lines
15 KiB
Groff
559 lines
15 KiB
Groff
.\" $FreeBSD$
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.\" $OpenBSD: dc.1,v 1.27 2012/08/19 12:07:21 jmc Exp $
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.\"
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.\" Copyright (C) Caldera International Inc. 2001-2002.
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code and documentation must retain the above
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.\" copyright notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed or owned by Caldera
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.\" International, Inc.
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.\" 4. Neither the name of Caldera International, Inc. nor the names of other
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.\" contributors may be used to endorse or promote products derived from
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.\" this software without specific prior written permission.
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.\"
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.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
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.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
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.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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.\" IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
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.\" INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" @(#)dc.1 8.1 (Berkeley) 6/6/93
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.\"
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.Dd February 27, 2017
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.Dt DC 1
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.Os
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.Sh NAME
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.Nm dc
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.Nd desk calculator
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.Sh SYNOPSIS
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.Nm
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.Op Fl hxV
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.Op Fl e Ar expression
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.Op Fl f Ar filename
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.Op Ar filename
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.Sh DESCRIPTION
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.Nm
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is an arbitrary precision arithmetic package.
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The overall structure of
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.Nm
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is
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a stacking (reverse Polish) calculator i.e.\&
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numbers are stored on a stack.
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Adding a number pushes it onto the stack.
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Arithmetic operations pop arguments off the stack
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and push the results.
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See also the
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.Xr bc 1
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utility, which is a preprocessor for
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.Nm
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providing infix notation and a C-like syntax
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which implements functions and reasonable control
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structures for programs.
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The options are as follows:
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.Bl -tag -width Ds
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.It Fl e Ar expr , Fl Fl expression Ar expr
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Evaluate
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.Ar expression .
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If multiple
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.Fl e
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options are specified, they will be processed in the order given.
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.It Fl f Ar filename , Fl Fl file Ar filename
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Process the content of the given file before further calculations are done.
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If multiple
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.Fl f
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options are specified, they will be processed in the order given.
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.It Fl h , Fl Fl help
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Print short usage info.
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.It Fl V , Fl Fl version
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Print version info.
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.It Fl x
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Enable extended register mode.
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This mode is used by
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.Xr bc 1
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to allow more than 256 registers.
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See
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.Sx Registers
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for a more detailed description.
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.El
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.Pp
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If neither
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.Ar expression
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nor
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.Ar file
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are specified on the command line,
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.Nm
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reads from the standard input.
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Otherwise
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.Ar expression
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and
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.Ar file
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are processed and
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.Nm
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exits.
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.Pp
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Ordinarily,
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.Nm
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operates on decimal integers,
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but one may specify an input base, output base,
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and a number of fractional digits (scale) to be maintained.
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Whitespace is ignored, except where it signals the end of a number,
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end of a line or when a register name is expected.
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The following constructions are recognized:
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.Bl -tag -width "number"
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.It Va number
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The value of the number is pushed on the stack.
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A number is an unbroken string of the digits 0\-9 and letters A\-F.
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It may be preceded by an underscore
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.Pq Sq _
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to input a negative number.
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A number may contain a single decimal point.
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A number may also contain the characters A\-F, with the values 10\-15.
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.It Cm "+ - / * % ~ ^"
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The
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top two values on the stack are added
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(+),
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subtracted
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(\-),
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multiplied (*),
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divided (/),
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remaindered (%),
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divided and remaindered (~),
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or exponentiated (^).
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The two entries are popped off the stack;
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the result is pushed on the stack in their place.
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Any fractional part of an exponent is ignored.
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.Pp
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For addition and subtraction, the scale of the result is the maximum
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of scales of the operands.
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For division the scale of the result is defined
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by the scale set by the
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.Ic k
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operation.
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For multiplication, the scale is defined by the expression
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.Sy min(a+b,max(a,b,scale)) ,
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where
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.Sy a
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and
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.Sy b
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are the scales of the operands, and
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.Sy scale
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is the scale defined by the
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.Ic k
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operation.
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For exponentiation with a non-negative exponent, the scale of the result is
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.Sy min(a*b,max(scale,a)) ,
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where
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.Sy a
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is the scale of the base, and
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.Sy b
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is the
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.Em value
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of the exponent.
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If the exponent is negative, the scale of the result is the scale
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defined by the
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.Ic k
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operation.
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.Pp
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In the case of the division and modulus operator (~),
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the resultant quotient is pushed first followed by the remainder.
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This is a shorthand for the sequence:
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.Bd -literal -offset indent -compact
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x y / x y %
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.Ed
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The division and modulus operator is a non-portable extension.
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.It Ic a
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Pop the top value from the stack.
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If that value is a number, compute the integer part of the number modulo 256.
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If the result is zero, push an empty string.
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Otherwise push a one character string by interpreting the computed value
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as an
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.Tn ASCII
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character.
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.Pp
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If the top value is a string, push a string containing the first character
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of the original string.
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If the original string is empty, an empty string is pushed back.
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The
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.Ic a
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operator is a non-portable extension.
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.It Ic c
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All values on the stack are popped.
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.It Ic d
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The top value on the stack is duplicated.
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.It Ic e
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Equivalent to
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.Ic p ,
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except that the output is written to the standard error stream.
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.It Ic f
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All values on the stack are printed, separated by newlines.
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.It Ic G
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The top two numbers are popped from the stack and compared.
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A one is pushed if the top of the stack is equal to the second number
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on the stack.
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A zero is pushed otherwise.
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This is a non-portable extension.
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.It Ic I
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Pushes the input base on the top of the stack.
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.It Ic i
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The top value on the stack is popped and used as the
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base for further input.
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The initial input base is 10.
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.It Ic J
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Pop the top value from the stack.
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The recursion level is popped by that value and, following that,
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the input is skipped until the first occurrence of the
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.Ic M
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operator.
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The
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.Ic J
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operator is a non-portable extension, used by the
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.Xr bc 1
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command.
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.It Ic K
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The current scale factor is pushed onto the stack.
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.It Ic k
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The top of the stack is popped, and that value is used as
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a non-negative scale factor:
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the appropriate number of places
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are printed on output,
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and maintained during multiplication, division, and exponentiation.
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The interaction of scale factor,
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input base, and output base will be reasonable if all are changed
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together.
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.It Ic L Ns Ar x
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Register
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.Ar x
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is treated as a stack and its top value is popped onto the main stack.
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.It Ic l Ns Ar x
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The
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value in register
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.Ar x
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is pushed on the stack.
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The register
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.Ar x
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is not altered.
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Initially, all registers contain the value zero.
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.It Ic M
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Mark used by the
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.Ic J
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operator.
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The
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.Ic M
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operator is a non-portable extensions, used by the
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.Xr bc 1
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command.
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.It Ic N
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The top of the stack is replaced by one if the top of the stack
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is equal to zero.
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If the top of the stack is unequal to zero, it is replaced by zero.
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This is a non-portable extension.
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.It Ic n
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The top value on the stack is popped and printed without a newline.
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This is a non-portable extension.
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.It Ic O
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Pushes the output base on the top of the stack.
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.It Ic o
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The top value on the stack is popped and used as the
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base for further output.
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The initial output base is 10.
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.It Ic P
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The top of the stack is popped.
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If the top of the stack is a string, it is printed without a trailing newline.
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If the top of the stack is a number, it is interpreted as a
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base 256 number, and each digit of this base 256 number is printed as
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an
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.Tn ASCII
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character, without a trailing newline.
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.It Ic p
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The top value on the stack is printed with a trailing newline.
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The top value remains unchanged.
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.It Ic Q
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The top value on the stack is popped and the string execution level is popped
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by that value.
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.It Ic q
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Exits the program.
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If executing a string, the recursion level is
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popped by two.
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.It Ic R
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The top of the stack is removed (popped).
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This is a non-portable extension.
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.It Ic r
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The top two values on the stack are reversed (swapped).
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This is a non-portable extension.
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.It Ic S Ns Ar x
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Register
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.Ar x
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is treated as a stack.
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The top value of the main stack is popped and pushed on it.
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.It Ic s Ns Ar x
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The
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top of the stack is popped and stored into
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a register named
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.Ar x .
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.It Ic v
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Replaces the top element on the stack by its square root.
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The scale of the result is the maximum of the scale of the argument
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and the current value of scale.
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.It Ic X
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Replaces the number on the top of the stack with its scale factor.
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If the top of the stack is a string, replace it with the integer 0.
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.It Ic x
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Treats the top element of the stack as a character string
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and executes it as a string of
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.Nm
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commands.
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.It Ic Z
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Replaces the number on the top of the stack with its length.
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The length of a string is its number of characters.
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The length of a number is its number of digits, not counting the minus sign
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and decimal point.
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.It Ic z
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The stack level is pushed onto the stack.
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.It Cm \&[ Ns ... Ns Cm \&]
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Puts the bracketed
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.Tn ASCII
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string onto the top of the stack.
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If the string includes brackets, these must be properly balanced.
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The backslash character
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.Pq Sq \e
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may be used as an escape character, making it
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possible to include unbalanced brackets in strings.
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To include a backslash in a string, use a double backslash.
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.It Xo
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.Cm < Ns Va x
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.Cm > Ns Va x
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.Cm = Ns Va x
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.Cm !< Ns Va x
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.Cm !> Ns Va x
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.Cm != Ns Va x
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.Xc
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The top two elements of the stack are popped and compared.
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Register
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.Ar x
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is executed if they obey the stated
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relation.
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.It Xo
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.Cm < Ns Va x Ns e Ns Va y
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.Cm > Ns Va x Ns e Ns Va y
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.Cm = Ns Va x Ns e Ns Va y
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.Cm !< Ns Va x Ns e Ns Va y
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.Cm !> Ns Va x Ns e Ns Va y
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.Cm != Ns Va x Ns e Ns Va y
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.Xc
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These operations are variants of the comparison operations above.
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The first register name is followed by the letter
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.Sq e
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and another register name.
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Register
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.Ar x
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will be executed if the relation is true, and register
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.Ar y
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will be executed if the relation is false.
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This is a non-portable extension.
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.It Ic \&(
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The top two numbers are popped from the stack and compared.
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A one is pushed if the top of the stack is less than the second number
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on the stack.
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A zero is pushed otherwise.
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This is a non-portable extension.
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.It Ic {
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The top two numbers are popped from the stack and compared.
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A one is pushed if the top of stack is less than or equal to the
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second number on the stack.
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A zero is pushed otherwise.
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This is a non-portable extension.
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.It Ic \&!
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Interprets the rest of the line as a
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.Ux
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command.
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.It Ic \&?
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A line of input is taken from the input source (usually the terminal)
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and executed.
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.It Ic \&: Ns Ar r
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Pop two values from the stack.
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The second value on the stack is stored into the array
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.Ar r
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indexed by the top of stack.
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.It Ic \&; Ns Ar r
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Pop a value from the stack.
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The value is used as an index into register
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.Ar r .
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The value in this register is pushed onto the stack.
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.Pp
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Array elements initially have the value zero.
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Each level of a stacked register has its own array associated with
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it.
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The command sequence
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.Bd -literal -offset indent
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[first] 0:a [dummy] Sa [second] 0:a 0;a p La 0;a p
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.Ed
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.Pp
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will print
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.Bd -literal -offset indent
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second
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first
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.Ed
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.Pp
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since the string
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.Ql second
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is written in an array that is later popped, to reveal the array that
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stored
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.Ql first .
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.It Ic #
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Skip the rest of the line.
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This is a non-portable extension.
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.El
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.Ss Registers
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Registers have a single character name
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.Ar x ,
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where
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.Ar x
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may be any character, including space, tab or any other special character.
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If extended register mode is enabled using the
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.Fl x
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option and the register identifier
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.Ar x
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has the value 255, the next two characters are interpreted as a
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two-byte register index.
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The set of standard single character registers and the set of extended
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registers do not overlap.
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Extended register mode is a non-portable extension.
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.Sh EXAMPLES
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An example which prints the first ten values of
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.Ic n! :
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.Bd -literal -offset indent
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[la1+dsa*pla10>y]sy
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0sa1
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lyx
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.Ed
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.Pp
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Independent of the current input base, the command
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.Bd -literal -offset indent
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Ai
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.Ed
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.Pp
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will reset the input base to decimal 10.
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.Sh DIAGNOSTICS
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.Bl -diag
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.It %c (0%o) is unimplemented
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an undefined operation was called.
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.It stack empty
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for not enough elements on the stack to do what was asked.
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.It stack register '%c' (0%o) is empty
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for an
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.Ar L
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operation from a stack register that is empty.
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.It Runtime warning: non-zero scale in exponent
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for a fractional part of an exponent that is being ignored.
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.It divide by zero
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for trying to divide by zero.
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.It remainder by zero
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for trying to take a remainder by zero.
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.It square root of negative number
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for trying to take the square root of a negative number.
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.It index too big
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for an array index that is larger than 2048.
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.It negative index
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for a negative array index.
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.It "input base must be a number between 2 and 16"
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for trying to set an illegal input base.
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.It output base must be a number greater than 1
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for trying to set an illegal output base.
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.It scale must be a nonnegative number
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for trying to set a negative or zero scale.
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.It scale too large
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for trying to set a scale that is too large.
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A scale must be representable as a 32-bit unsigned number.
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.It Q command argument exceeded string execution depth
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for trying to pop the recursion level more than the current
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recursion level.
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.It Q command requires a number >= 1
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for trying to pop an illegal number of recursion levels.
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.It recursion too deep
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for too many levels of nested execution.
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.Pp
|
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The recursion level is increased by one if the
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.Ar x
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or
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.Ar ?\&
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operation or one of the compare operations resulting in the execution
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of register is executed.
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As an exception, the recursion level is not increased if the operation
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is executed as the last command of a string.
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For example, the commands
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.Bd -literal -offset indent
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[lax]sa
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1 lax
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.Ed
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.Pp
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|
will execute an endless loop, while the commands
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.Bd -literal -offset indent
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[laxp]sa
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1 lax
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.Ed
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.Pp
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will terminate because of a too deep recursion level.
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.It J command argument exceeded string execution depth
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for trying to pop the recursion level more than the current
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recursion level.
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.It mark not found
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for a failed scan for an occurrence of the
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.Ic M
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operator.
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.El
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.Sh SEE ALSO
|
|
.Xr bc 1
|
|
.Pp
|
|
.An -nosplit
|
|
.An L. L. Cherry ,
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.An R. Morris
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|
"DC \- An Interactive Desk Calculator"
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|
.Pa /usr/share/doc/usd/05.dc/ .
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.Sh STANDARDS
|
|
The arithmetic operations of the
|
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.Nm
|
|
utility are expected to conform to the definition listed in the
|
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.Xr bc 1
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|
section of the
|
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.St -p1003.2
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|
specification.
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.Sh HISTORY
|
|
The
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.Nm
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|
command first appeared in
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.At v6 .
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A complete rewrite of the
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.Nm
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|
command using the
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.Xr bn 3
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|
big number routines first appeared in
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.Ox 3.5 .
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.Sh AUTHORS
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.An -nosplit
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The original version of the
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.Nm
|
|
command was written by
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.An Robert Morris
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and
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.An Lorinda Cherry .
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The current version of the
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.Nm
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|
utility was written by
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.An Otto Moerbeek .
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