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