'\" te
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.TH bc 1 "29 Aug 2003" "SunOS 5.11" "User Commands"
.SH NAME
bc \- arbitrary precision arithmetic language
.SH SYNOPSIS
.LP
.nf
\fB/usr/bin/bc\fR [\fB-c\fR] [\fB-l\fR] [\fIfile\fR]...
.fi

.LP
.nf
\fB/usr/xpg6/bin/bc\fR [\fB-c\fR] [\fB-l\fR] [\fIfile\fR]...
.fi

.SH DESCRIPTION
.sp
.LP
The \fBbc\fR utility implements an arbitrary precision calculator. It takes
input from any files given, then reads from the standard input. If the standard
input and standard output to \fBbc\fR are attached to a terminal, the
invocation of \fBbc\fR is  \fIinteractive\fR, causing behavioral constraints
described in the following sections. \fBbc\fR processes a language that
resembles C and is a preprocessor for the desk calculator program \fBdc\fR,
which it invokes automatically unless the \fB-c\fR option is specified. In this
case the \fBdc\fR input is sent to the standard output instead.
.SH USAGE
.sp
.LP
The syntax for  \fBbc\fR programs is as follows:
.sp
.ne 2
.mk
.na
\fB\fIL\fR\fR
.ad
.RS 5n
.rt  
Means a letter \fBa\fR\(mi\fBz\fR,
.RE

.sp
.ne 2
.mk
.na
\fB\fIE\fR\fR
.ad
.RS 5n
.rt  
Means an expression: a (mathematical or logical) value, an operand  that takes
a value, or a combination of operands and operators that evaluates to a value,
.RE

.sp
.ne 2
.mk
.na
\fB\fIS\fR\fR
.ad
.RS 5n
.rt  
Means a statement.
.RE

.SS "Comments"
.sp
.LP
Enclosed in \fB/*\fR and \fB*/\fR.
.SS "Names (Operands)"
.br
.in +2
Simple variables: \fIL\fR.
.in -2
.br
.in +2
Array elements: \fIL\fR [ \fIE\fR ] (up to \fBBC_DIM_MAX\fR dimensions).
.in -2
.br
.in +2
The words \fBibase\fR, \fBobase\fR (limited to \fBBC_BASE_MAX\fR), and
\fBscale\fR (limited to \fBBC_SCALE_MAX\fR).
.in -2
.SS "Other Operands"
.sp
.LP
Arbitrarily long numbers with optional sign and decimal point. Strings of fewer
than \fBBC_STRING_MAX\fR characters, between double quotes ("). \fB(\fR \fIE\fR
\fB)\fR
.sp
.ne 2
.mk
.na
\fB\fBsqrt ( \fR\fIE\fR\fB )\fR\fR
.ad
.RS 21n
.rt  
Square root
.RE

.sp
.ne 2
.mk
.na
\fB\fBlength ( \fR\fIE\fR\fB )\fR\fR
.ad
.RS 21n
.rt  
Number of significant decimal digits.
.RE

.sp
.ne 2
.mk
.na
\fB\fBscale ( \fR\fIE\fR\fB )\fR\fR
.ad
.RS 21n
.rt  
Number of digits right of decimal point.
.RE

.sp
.ne 2
.mk
.na
\fB\fIL \fR\fB( \fR\fIE\fR , ... , \fIE\fR\fB )\fR\fR
.ad
.RS 21n
.rt  
 
.RE

.SS "Operators"
.sp
.ne 2
.mk
.na
\fB\fB+   \(mi   *   /   %   ^\fR\fR
.ad
.sp .6
.RS 4n
(\fB%\fR is remainder; \fB^\fR is power)
.RE

.sp
.ne 2
.mk
.na
\fB\fB++   \(mi\(mi \fR\fR
.ad
.sp .6
.RS 4n
(prefix and postfix; apply to names)
.RE

.sp
.ne 2
.mk
.na
\fB\fB==   <=   >=   !=   <   >\fR\fR
.ad
.sp .6
.RS 4n
 
.RE

.sp
.ne 2
.mk
.na
\fB\fB=   =+   =\(mi   =*   =/   =%   =^\fR\fR
.ad
.sp .6
.RS 4n
 
.RE

.SS "Statements"
.br
.in +2
\fIE\fR
.in -2
.br
.in +2
\fB{\fR \fIS\fR \fB;\fR.\|.\|. \fB;\fR \fIS\fR \fB}\fR
.in -2
.br
.in +2
\fBif (\fR \fIE\fR \fB)\fR \fIS\fR
.in -2
.br
.in +2
\fBwhile (\fR \fIE\fR \fB)\fR \fIS\fR
.in -2
.br
.in +2
\fBfor (\fR \fIE\fR \fB;\fR \fIE\fR \fB;\fR \fIE\fR \fB)\fR \fIS\fR
.in -2
.br
.in +2
null statement
.in -2
.br
.in +2
\fBbreak\fR
.in -2
.br
.in +2
\fBquit\fR
.in -2
.sp
.LP
\&.string
.SS "Function Definitions"
.br
.in +2
\fBdefine\fR \fIL\fR \fB(\fR \fIL\fR \fB,\fR.\|.\|.\|\fB,\fR \fIL\fR \fB) {\fR
.in -2
.br
.in +2
\fB	auto\fR \fIL\fR \fB,\fR.\|.\|.\|\fB,\fR \fIL\fR
.in -2
.br
.in +2
\fI	S\fR \fB;\fR.\|.\|.\| \fIS\fR
.in -2
.br
.in +2
\fB	return (\fR \fIE\fR \fB)\fR
.in -2
.br
.in +2
\fB}\fR
.in -2
.SS "Functions in \fB-l\fR Math Library"
.sp
.ne 2
.mk
.na
\fB\fBs(\fR\fIx\fR\fB)\fR\fR
.ad
.RS 10n
.rt  
sine
.RE

.sp
.ne 2
.mk
.na
\fB\fBc(\fR\fIx\fR\fB)\fR\fR
.ad
.RS 10n
.rt  
cosine
.RE

.sp
.ne 2
.mk
.na
\fB\fBe(\fR\fIx\fR\fB)\fR\fR
.ad
.RS 10n
.rt  
exponential
.RE

.sp
.ne 2
.mk
.na
\fB\fBl(\fR\fIx\fR\fB)\fR\fR
.ad
.RS 10n
.rt  
log
.RE

.sp
.ne 2
.mk
.na
\fB\fBa(\fR\fIx\fR\fB)\fR\fR
.ad
.RS 10n
.rt  
arctangent
.RE

.sp
.ne 2
.mk
.na
\fB\fBj(\fR\fIn\fR\fB,\fR\fIx)\fR\fR
.ad
.RS 10n
.rt  
Bessel function
.RE

.sp
.LP
All function arguments are passed by value.
.sp
.LP
The value of a statement that is an expression is printed unless the main
operator is an assignment. Either semicolons or new-lines may separate
statements. Assignment to \fBscale\fR influences the number of digits to be
retained on arithmetic operations in the manner of \fBdc\fR. Assignments to
\fBibase\fR or \fBobase\fR set the input and output number radix respectively.
.sp
.LP
The same letter may be used as an array, a function, and a simple variable
simultaneously. All variables are global to the program. \fBauto\fR variables
are stacked during function calls. When using arrays as function arguments or
defining them as automatic variables, empty square brackets must follow the
array name.
.SH OPTIONS
.sp
.LP
The following operands are supported:
.sp
.ne 2
.mk
.na
\fB\fB-c\fR\fR
.ad
.RS 6n
.rt  
Compiles only. The output is \fBdc\fR commands that are sent to the standard
output.
.RE

.SS "/usr/bin/bc"
.sp
.ne 2
.mk
.na
\fB\fB-l\fR\fR
.ad
.RS 6n
.rt  
Defines the math functions and initializes \fBscale\fR to \fB20\fR, instead of
the default zero.
.RE

.SS "/usr/xpg6/bin/bc"
.sp
.ne 2
.mk
.na
\fB\fB-l\fR\fR
.ad
.RS 6n
.rt  
Defines the math functions and initializes \fBscale\fR to \fB20\fR, instead of
the default zero. All math results have the scale of \fB20\fR.
.RE

.SH OPERANDS
.sp
.LP
The following operands are supported:
.sp
.ne 2
.mk
.na
\fB\fIfile\fR\fR
.ad
.RS 8n
.rt  
A pathname of a text file containing \fBbc\fR program statements. After all
cases of \fIfile\fR have been read, \fBbc\fR reads the standard input.
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fRSetting the precision of a variable
.sp
.LP
In the shell, the following assigns an approximation of the first ten digits of
\fBn\fR to the variable \fIx\fR:

.sp
.in +2
.nf
\fBx=$(printf "%s\en" 'scale = 10; 104348/33215' | bc)\fR
.fi
.in -2
.sp

.LP
\fBExample 2 \fRDefining a computing function
.sp
.LP
Defines a function to compute an approximate value of the exponential function:

.sp
.in +2
.nf
\fBscale = 20
define e(x){
	auto a, b, c, i, s
	a = 1
	b = 1
	s = 1
	for(i=1; 1==1; i++){
		a = a*x
		b = b*i
		c = a/b
		if(c == 0) return(s)
		s = s+c
	}
}\fR
.fi
.in -2
.sp

.LP
\fBExample 3 \fRPrinting the approximate values of the function
.sp
.LP
Prints approximate values of the exponential function of the first ten
integers:

.sp
.in +2
.nf
\fBfor(i=1; i<=10; i++) e(i)\fR
.fi
.in -2
.sp

.sp
.LP
or

.sp
.in +2
.nf
\fBfor (i = 1; i <= 10; ++i) {         e(i) }\fR
.fi
.in -2
.sp

.SH ENVIRONMENT VARIABLES
.sp
.LP
See \fBenviron\fR(5) for descriptions of the following environment variables
that affect the execution of \fBbc\fR: \fBLANG\fR, \fBLC_ALL\fR,
\fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
.SH EXIT STATUS
.sp
.LP
The following exit values are returned:
.sp
.ne 2
.mk
.na
\fB\fB0\fR\fR
.ad
.RS 15n
.rt  
All input files were processed successfully.
.RE

.sp
.ne 2
.mk
.na
\fB\fBunspecified\fR\fR
.ad
.RS 15n
.rt  
An error occurred.
.RE

.SH FILES
.sp
.ne 2
.mk
.na
\fB\fB/usr/lib/lib.b\fR\fR
.ad
.RS 25n
.rt  
mathematical library
.RE

.sp
.ne 2
.mk
.na
\fB\fB/usr/include/limits.h\fR\fR
.ad
.RS 25n
.rt  
to define BC_ parameters
.RE

.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityStandard
.TE

.SH SEE ALSO
.sp
.LP
\fBdc\fR(1), \fBawk\fR(1), \fBattributes\fR(5), \fBenviron\fR(5),
\fBstandards\fR(5)
.SH NOTES
.sp
.LP
The \fBbc\fR command does not recognize the logical operators \fB&&\fR and
\fB|\||\fR.
.sp
.LP
The \fBfor\fR statement must have all three expressions (\fIE\fR's).