bc(1)
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bc Command
arbitrary-precision arithmetic language
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SYNTAX
bc [ -c ] [ -l ] [ file ... ]
DESCRIPTION
Bc is an interactive processor for a language that resembles C
but provides essentially 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 programs is as follows; L means
letters a-z, E means expression, and S means statement.
Comments
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
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bc(1)
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 new-
lines may separate 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.
You can use the same letter as an array, a function, and a simple
variable 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, you must place empty square brackets after
the array name.
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 output
instead. Bc is terminated by CRTL-D (^d).
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EXAMPLES
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bc(1)
$ bc
scale=5 <nl>
12567/234 <nl>
53.70512
The processor returns the result of the expression.
$
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This example divides 12567 by 234 and prints the result with a
precision of 5 decimal places.
FILES
/usr/lib/lib.b Mathematical library
/usr/bin/dc Desk calculator
SEE ALSO
dc(1).
BUGS
&& and || are not implemented in DG/UX.
For statement must have all three Es.
Quit is interpreted when read, not when executed.
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