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 in-
          put from any files given, then reads the standard input.
          The -l argument stands for the name of an arbitrary preci-
          sion math library.  The syntax for bc programs is as fol-
          lows:  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



     April, 1990                                                     1

     bc(1)                                                       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 ar-
          ithmetic operations in the manner of dc(1).  Assignments to
          ibase or obase set the input and output number radix respec-
          tively.

          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 fol-
          low the array name.

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

     EXAMPLES
          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




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     bc(1)                                                       bc(1)



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

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

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

     SEE ALSO
          dc(1).
          ``bc Reference'' in A/UX Programming Languages and Tools,
          Volume 2.

     BUGS
          No && or || yet.

          for statement must have all three E's.

          quit is interpreted when read, not when executed.


































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