SunOS man pages : bc (1)
User Commands bc(1)
NAME
bc  arbitrary precision arithmetic language
SYNOPSIS
bc [ c ] [ l ] [ file ... ]
DESCRIPTION
The bc utility implements an arbitrary precision calculator.
It takes input from any files given, then reads from the
standard input. If the standard input and standard output to
bc are attached to a terminal, the invocation of bc is
interactive, causing behavioral constraints described in the
following sections. bc processes a language that resembles C
and is a preprocessor for the desk calculator program dc,
which it invokes automatically unless the c option is
specified. In this case the dc input is sent to the stan
dard output instead.
USAGE
The syntax for bc programs is as follows:
L means a letter az,
E means an expression: a (mathematical or logical)
value, an operand that takes a value, or a combina
tion of operands and operators that evaluates to a
value,
S means a statement.
Comments
Enclosed in /* and */.
Names (Operands)
Simple variables: L.
Array elements: L [ E ] (up to BC_DIM_MAX dimen
sions).
The words ibase, obase (limited to BC_BASE_MAX),
and scale (limited to BC_SCALE_MAX).
Other Operands
Arbitrarily long numbers with optional sign and decimal
point. Strings of fewer than BC_STRING_MAX characters,
between double quotes ("). ( E )
sqrt ( E )
Square root
length ( E )
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User Commands bc(1)
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
.string
Function Definitions
define L ( L ,..., L ) {
auto L ,..., L
S ;... S
return ( E )
}
Functions in l Math Library
s(x) sine
c(x) cosine
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User Commands bc(1)
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. 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 stacked during function
calls. When using arrays as function arguments or defining
them as automatic variables, empty square brackets must fol
low the array name.
OPTIONS
The following operands are supported:
c Compile only. The output is dc commands that are sent
to the standard output.
l Define the math functions and initialize scale to 20,
instead of the default zero.
OPERANDS
The following operands are supported:
file A pathname of a text file containing bc program state
ments. After all cases of file have been read, bc will
read the standard input.
EXAMPLES
Example 1: Setting the precision of a variable
In the shell, the following assigns an approximation of the
first ten digits of n to the variable x:
x=$(printf "%s\n" 'scale = 10; 104348/33215'  bc)
Example 2: Defining a computing function
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User Commands bc(1)
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
}
}
Example 3: Printing the approximate values of the function
Prints approximate values of the exponential function of the
first ten integers:
for(i=1; i<=10; i++) e(i)
or
for (i = 1; i <= 10; ++i) { e(i) }
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment
variables that affect the execution of bc: LC_CTYPE,
LC_MESSAGES, and NLSPATH.
EXIT STATUS
The following exit values are returned:
0 All input files were processed successfully.
unspecified
An error occurred.
FILES
/usr/lib/lib.b
mathematical library
/usr/include/limits.h
to define BC_ parameters
ATTRIBUTES
See attributes(5) for descriptions of the following attri
butes:
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User Commands bc(1)
____________________________________________________________
 ATTRIBUTE TYPE  ATTRIBUTE VALUE 
__________________________________________________________
 Availability  SUNWesu 
__________________________________________________________
SEE ALSO
dc(1), awk(1), attributes(5)
NOTES
The bc command does not recognize the logical operators &&
and .
The for statement must have all three expressions (E's).
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