4.4BSD/usr/src/usr.bin/bc/bc.1

.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This module is believed to contain source code proprietary to AT&T.
.\" Use and redistribution is subject to the Berkeley Software License
.\" Agreement and your Software Agreement with AT&T (Western Electric).
.\"
.\"	@(#)bc.1	8.1 (Berkeley) 6/29/93
.\"
.Dd June 29, 1993
.Dt BC 1
.Os ATT 7th
.Sh NAME
.Nm \&bc
.Nd arbitrary-precision arithmetic language and calculator
.Sh SYNOPSIS
.Nm \&bc
.Op Fl c
.Op Fl l
.Ar
.Sh DESCRIPTION
.Nm \&Bc
is an interactive processor for a language which resembles
C but provides unlimited precision arithmetic.
It takes input from any files given, then reads
the standard input.
.Pp
Options available:
.Bl -tag -width flag
.It Fl l
allow specification
of an arbitrary precision math library.
.It Fl c
.Nm \&Bc
is actually a preprocessor for
.Ar \&dc 1 ,
which it invokes automatically, unless the
.Fl c
compile only option is present.
Here, the
.Ar \&dc
input is sent to the standard output instead.
.El 
.Pp
The syntax for
.Nm \&bc
programs is as follows;
L means letter a-z,
E means expression, S means statement.
.Pp
Comments
.Bd -unfilled -offset indent -compact
are enclosed in /* and */.
.Ed
.Pp
Names
.Bd -unfilled -offset indent -compact
simple variables: L
array elements: L [ E ]
The words `ibase', `obase', and `scale'
.Ed
.Pp
Other operands
.Bd -unfilled -offset indent -compact
arbitrarily long numbers with optional sign and decimal point.
\&( E \&)
sqrt ( E )
length ( E )	number of significant decimal digits
scale ( E )	number of digits right of decimal point
L ( E , ... , E )
.Ed
.Pp
Operators
.Bd -unfilled -offset indent -compact
\&+  \-  *  /  %  ^ (% is remainder; ^ is power)
\&++   \-\-         (prefix and postfix; apply to names)
\&==  <=  >=  !=  <  >
\&=  +=  \-=  *=  /=  %=  ^=
.Ed
.Pp
Statements
.Bd -unfilled -offset indent -compact
E
{ S ; ... ; S }
if ( E ) S
while ( E ) S
for ( E ; E ; E ) S
null statement
break
quit
.Ed
.Pp
Function definitions
.Bd -unfilled -offset indent -compact
define L ( L ,..., L ) {
	auto L, ... , L
	S; ... S
	return ( E )
}
.Ed
.Pp
Functions in
.Fl l
math library
.Bl -tag -width j(n,x) -offset indent -compact
.It s(x)
sine
.It c(x)
cosine
.It e(x)
exponential
.It l(x)
log
.It a(x)
arctangent
.It j(n,x)
Bessel function
.El
.Pp
All function arguments are passed by value.
.Pp
The value of a statement that is an expression is printed
unless the main operator is an assignment.
Either semicolons or newlines may separate statements.
Assignment to
.Ar scale
influences the number of digits to be retained on arithmetic
operations in the manner of
.Xr \&dc 1 .
Assignments to
.Ar ibase
or
.Ar obase
set the input and output number radix respectively.
.Pp
The same letter may be used as an array, a function,
and a simple variable simultaneously.
All variables are global to the program.
`Auto' variables are pushed down during function calls.
When using arrays as function arguments
or defining them as automatic variables,
empty square brackets must follow the array name.
.Pp
For example
.Bd -literal -offset indent
scale = 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
	}
}
.Ed
.Pp
defines a function to compute an approximate value of
the exponential function and
.Pp
.Dl for(i=1; i<=10; i++) e(i)
.Pp
prints approximate values of the exponential function of
the first ten integers.
.Sh FILES
.\" /usr/lib/lib.b	mathematical library
.Bl -tag -width xxxxx -compact
.It Xr \&dc 1
Desk calculator proper.
.El
.Sh SEE ALSO
.Xr \&dc 1
.Rs
.%A L. L. Cherry
.%A R. Morris
.%T "BC \- An arbitrary precision desk-calculator language"
.Re
.Sh HISTORY
The
.Nm \&bc
command appeared in
.At v6 .
.Sh BUGS
No &&, ||, or ! operators.
.Pp
.Ql For
statement must have all three E's.
.Pp
.Ql Quit
is interpreted when read, not when executed.