bc(1)bc(1)NAMEbc - arbitrary-precision arithmetic language
SYNOPSIS
[file...]
DESCRIPTION
is an interactive processor for a language that resembles C but pro‐
vides unlimited-precision arithmetic. It takes input from any files
given, then reads the standard input.
Options
recognizes the following command-line options:
Compile only.
is actually a preprocessor for which invokes automati‐
cally (see dc(1)). Specifying prevents invoking dc,
and sends the dc input to standard output.
causes an arbitrary-precision math library to be predefined.
As a side effect, the scale factor is set.
Program Syntax
L a single letter in the range through
E expression;
S statement;
R relational expression.
Comments
Comments are enclosed in and
Names
Names include:
simple variables: L
array elements: L [ E ]
stacks: L
Other Operands
Other operands include:
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 dec‐
imal point
L ( E , ... , E )
Strings of ASCII characters enclosed in quotes
("").
Arithmetic Operators:
Arithmetic operators yield an E as a result and include:
is remainder (not mod, see below); is power).
(prefix and append; apply to names)
Relational Operators
Relational operators yield an R when used as op
Statements
E
{ S ; ... ; S }
if ( R ) S
while ( R ) S
for ( E ; R ; E ) S
null statement
break
quit
Function Definitions
define L ( L ,..., L ) {
auto L, ... , L
S; ... S
return ( E )
}
Functions in −l Math Library
Functions in the math library include:
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. Trigonomet‐
ric angles are in radians where 2 pi radians = 360
degrees.
The value of a statement that is an expression is printed
unless the main operator is an assignment. No operators
are defined for strings, but the string is printed if it
appears in a context where an expression result would be
printed. Either semicolons or new-lines can separate
statements. Assignment to scale influences the number of
digits to be retained on arithmetic operations in the
manner of dc(1). Assignments to or set the input and
output number radix respectively, again as defined by
dc(1).
The same letter can be used simultaneously as an array, a
function, and a simple variable. 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.
The operator yields the remainder at the current scale,
not the integer modulus. Thus, at scale 1, is .1 (one
tenth), not 1. This is because (at scale 1) is 2.3 with
.1 as the remainder.
EXAMPLES
Define a function to compute an approximate value of the
exponential function:
Print approximate values of the exponential function of
the first ten integers.
WARNINGS
There are currently no (AND) or (OR) comparisons.
The statement must have all three expressions.
is interpreted when read, not when executed.
parser is not robust in the face of input errors. Some
simple expression such as 2+2 helps get it back into
phase.
The assignment operators: and are obsolete. Any
occurences of these operators cause a syntax error with
the exception of which is interpreted as followed by a
unary minus.
Neither entire arrays nor functions can be passed as
function parameters.
FILES
desk calculator executable program
mathematical library
SEE ALSObs(1), dc(1).
tutorial in
STANDARDS CONFORMANCEbc(1)