# 2.11BSD#431 - /usr/man/cat1/bc.0

    BC(1)		    UNIX Programmer's Manual		    BC(1)

    NAME
         bc - arbitrary-precision arithmetic language

    SYNOPSIS
         bc [ -c ] [ -l ] [ file ... ]

    DESCRIPTION
         Bc is an interactive processor for a language which resem-
         bles 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 letter a-z, E means expression, S means
         statement.

         Comments
    	   are 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
    	   quit

         Function definitions
    	   define L ( L ,..., L ) {
    		auto L, ... , L
    		S; ... S

    Printed 11/26/99	October 21, 1996			1

    BC(1)		    UNIX Programmer's Manual		    BC(1)

    		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 semi-
         colons or newlines 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.

         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 func-
         tion calls.  When using arrays as function arguments or
         defining them as automatic variables empty square brackets
         must follow the array name.

         For example

         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
    	  }
         }

         defines a function to compute an approximate value of the
         exponential function and

    	  for(i=1; i<=10; i++) e(i)

         prints approximate values of the exponential function of the
         first ten integers.

    Printed 11/26/99	October 21, 1996			2

    BC(1)		    UNIX Programmer's Manual		    BC(1)

         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.

    FILES
         /usr/share/misc/lib.b mathematical library
         dc(1)		   desk calculator proper

    SEE ALSO
         dc(1)
         L. L. Cherry and R. Morris, BC - An arbitrary precision
         desk-calculator language

    BUGS
         No &&, ||, or ! operators.
         For statement must have all three E's.
         Quit is interpreted when read, not when executed.

    Printed 11/26/99	October 21, 1996			3

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