NAME
bc - arbitrary-precision arithmetic language and calculator

SYNOPSIS
bc [ -c ] [ -l ] [ file ... ]

DESCRIPTION
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. The -l argument stands
for the name of an arbitrary precision math library. The syntax
for bc programs is as follows; L means letter a-z, E means
expression, S means statement.

Comments
are enclosed in /* and */.

Names
simple variables: L
array elements: L [ E ]
The words ‘ibase’, ‘obase’, and ‘scale’

Other operands
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 )

Operators
+ - * / % ^ (% is remainder; ^ is power)
++ -- (prefix and postfix; apply to names)
== <= >= != < >
= += -= *= /= %= ^=

Statements
E
{ S ; ... ; S }
if ( E ) S
while ( E ) S
for ( E ; E ; E ) S
null statement
break
quit

Function definitions
define L ( L ,..., L ) {
auto L, ... , L
S; ... S
return ( E )
}

Functions in -l math library
s(x) sine
c(x) cosine
e(x) exponential
l(x) log
a(x) arctangent
j(n,x) Bessel function

All function arguments are passed by value.

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 scale influences the number
of digits to be retained on arithmetic operations in the manner of
dc(1). Assignments to ibase or obase set the input and output
number radix respectively.

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.

For example

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
}
}

defines a function to compute an approximate value of the
exponential function and

for(i=1; i<=10; i++) e(i)

prints approximate values of the exponential function of the first
ten integers.

Bc is actually a preprocessor for dc(1), which it invokes
automatically, unless the -c (compile only) option is present. In
this case the dc input is sent to the standard output instead.

FILES
/usr/lib/lib.b mathematical library
dc(1) desk calculator proper

SEE ALSO
dc(1)
L. L. Cherry and R. Morris, "BC - An Arbitrary Precision Desk-
Calculator Language" (see MachTen Unix Basics manual)

BUGS
No &&, ||, or ! operators.
For statement must have all three E’s.
Quit is interpreted when read, not when executed.