BC(1) General Commands Manual BC(1)
NAME
bc  arbitraryprecision arithmetic language
SYNOPSIS
bc [ c ] [ l ] [ filename...]
DESCRIPTION
bc is an interactive processor for a language which resembles C but
provides unlimited precision arithmetic. bc takes input from any files
given, then reads the standard input.
OPTIONS
c Compile only. 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 out
put instead.
l Is the name of an arbitrary precision math library.
USAGE
Comments
Enclosed in /* and */.
Names
Simple variables: l, where, l is a lowercase letter.
Array elements: l[expression], where, expression is a legal bc expres
sion.
The words ibase, obase, and scale.
Other Operands
Arbitrarily long numbers with optional sign and decimal point.
(expression)
sqrt (expression)
length (expression) Number of significant decimal digits
scale (expression) Number of digits right of decimal point
l(expression, ..., expression)
Operators
+  * / % ^ (% is remainder; ^ is exponent)
++  (prefix and postfix; apply to names)
== <<= >>= != << >>
= += = *= /= %= ^=
Statements
expression
{statement; ...; statement}
where, statement is a legal bc statement.
if (expression)statement
while ( expression ) statement
for ( expression ; expression ; expression ) statement
null statement
break
quit
Function Definitions
define l ( l,...,l ) {
auto l ,..., l
statement ;... statement
return ( expression ) }
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 sep
arate 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 vari
able 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.
EXAMPLES
Define a function to compute an approximate value of the exponential
function:
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
}
}
Print approximate values of the exponential function of the first ten
integers:
for(i=1; i<<=10; i++) e(i)
FILES
/usr/lib/lib.b mathematical library
dc(1) desk calculator proper
SEE ALSO
dc(1)
BUGS
for statement must have all three expression's.
quit is interpreted when read, not when executed.
24 September 1987 BC(1)
