BC(1)                                SysV                                BC(1)



NAME
     bc - arbitrary-precision arithmetic language

SYNOPSIS
     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 bc(1) utility is actually a
     preprocessor for dc(1), which it invokes automatically unless the -c
     option is present.  In this case the dc input is sent to the standard
     output instead.

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

PROGRAM SYNTAX
     The syntax for bc programs is shown below; (L means letter 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 )

     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
                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.

OPTIONS
     -c        Compile only.  The output is send to the standard output.

     -l        Argument stands for the name of an arbitrary precision math
               library.

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.

BUGS
     The bc command does not yet recognize the logical operators, && and ||.
     For statement must have all three expressions (E's).
     Quit is interpreted when read, not when executed.

FILES
     /usr/lib/lib.b mathematical library
     /usr/bin/dc    desk calculator proper

SEE ALSO
     dc(1).