BC(C) XENIX System V BC(C)
Name
bc - Invokes a calculator.
Syntax
bc [ -c ] [ -l ] [ file ... ]
Description
bc is an interactive processor for a language that 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 programs is as
follows: L means the letters a-z, E means expression, 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 )
Additive operators:
+
-
Multiplicative operators:
*
/
% (remainder)
^ (exponentiation)
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BC(C) XENIX System V BC(C)
Unary operators:
++
- - (prefix and postfix; apply to names)
Relational operators:
==
<=
>=
!=
<
>
Assignment operators:
=
=+
=-
=*
=/
=%
=^
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 )
}
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BC(C) XENIX System V BC(C)
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 separate statements. Assignment
to scale influences the number of digits to be retained on
arithmetic operations in the manner of dc(C). 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 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, empty square brackets
must follow the array name.
bc is actually a preprocessor for dc(C), which it invokes
automatically, unless the -c (compile only) option is
present. If the -c option is present, the dc input is sent
to the standard output instead.
Example
The following defines 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
}
}
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BC(C) XENIX System V BC(C)
The following prints the approximate values of the
exponential function of the first ten integers:
for(i=1; i<=10; i++) e(i)
Files
/usr/lib/lib.bc Mathematical library
/usr/bin/dc Desk calculator proper
See Also
dc(C)
The XENIX User's Guide
Notes
A For statement must have all three E's.
Quit is interpreted when read, not when executed.
Trigonometric values should be given in radians.
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