BC(1)                                                       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 options are as follows:

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

          -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



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     BC(1)                                                       BC(1)



                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.

          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.

     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
               }
          }



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     BC(1)                                                       BC(1)



          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.

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

     SEE ALSO
          dc(1).

     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.

     ORIGIN
          AT&T V.3
































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