NAME
bc - arbitrary precision interactive language
SYNOPSIS
bc [ -l ] [ file ... ]
DESCRIPTION
Bc is an interactive processor for a language which resem-
bles 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 fol-
lows; 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 deci-
mal 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 )
}
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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 semi-
colons 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' vari-
ables 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.b mathematical 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.
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