bc(1)								   User Commands							     bc(1)

NAME

       bc - arbitrary precision arithmetic language

SYNOPSIS

       /usr/bin/bc [-c] [-l] [file]...

       /usr/xpg6/bin/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  con-
       straints  described  in the following sections. bc processes a language that resembles C and is a preprocessor for the desk calculator pro-
       gram dc, which it invokes automatically unless the -c option is specified. In this case the  dc	input  is  sent  to  the  standard  output
       instead.

USAGE

       The syntax for  bc programs is as follows:

       L    Means a letter a-z,

       E    Means  an  expression:  a  (mathematical or logical) value, an operand  that takes a value, or a combination 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 dimensions).
	 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 )	    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

       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.
       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 follow the array name.

OPTIONS

       The following operands are supported:

       -c    Compiles only. The output is dc commands that are sent to the standard output.

   /usr/bin/bc
       -l    Defines the math functions and initializes scale to 20, instead of the default zero.

   /usr/xpg6/bin/bc
       -l    Defines the math functions and initializes scale to 20, instead of the default zero. All math results have the scale of 20.

OPERANDS

       The following operands are supported:

       file    A pathname of a text file containing bc program statements. After all cases of file have been read, bc reads 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
" 'scale = 10; 104348/33215' | bc)

       Example 2 Defining a computing function

       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: LANG, LC_ALL, LC_CTYPE, LC_MES-
       SAGES, 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 attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWesu			   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       dc(1), awk(1), attributes(5), environ(5), standards(5)

NOTES

       The bc command does not recognize the logical operators && and ||.

       The for statement must have all three expressions (E's).

SunOS 5.11							    29 Aug 2003 							     bc(1)