NAME

bc − arbitrary precision interactive language

SYNOPSIS

bc [ −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 a library of mathematical subroutines which contains sine (named ‘s’), cosine (‘c’), arctangent (‘a’), natural logarithm (‘l’), and exponential (‘e’).  The syntax for bc programs is as follows; E means expression, S means statement. 

Comments
are enclosed in /* and */.

Names
letters a−z
array elements: letter[E]
The words ‘ibase’, ‘obase’, and ‘scale’

Other operands
arbitrarily long numbers with optional sign and decimal point.
( E )
sqrt ( E )
<letter> ( E , ... , E )

Operators
+  −  *  /  %  ^
++   −−         (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 are exemplified by
define <letter> ( <letter> ,..., <letter> ) {
auto <letter>, ... , <letter>
S; ... S
return ( E )
}

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.  Assignments to ibase or obase set the input and output number radix respectively.  The same letter may be used as an array name, a function name, and a simple variable simultaneously. ‘Auto’ variables are saved and restored during function calls. All other variables are global to the program. 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.

FILES

/usr/lib/lib.bmathematical library

SEE ALSO

dc (I), C Reference Manual, “BC − An Arbitrary Precision Desk-Calculator Language.”

BUGS

No &&, | | yet. 
for statement must have all three E’s
quit is interpreted when read, not when executed.