BC(1)BC(1)NAMEbc - arbitrary-precision arithmetic language
SYNOPSISbc [ -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 pro‐
grams 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 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.
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 automati‐
cally, 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 ALSOdc(1)
L. L. Cherry and R. Morris, BC - An arbitrary precision desk-calculator
language
BUGS
No &&, ||, or ! operators.
For statement must have all three E's.
Quit is interpreted when read, not when executed.
BC(1)
