BC(1)               RISC/os Reference Manual                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.
     bc is actually a preprocessor for the desk calculator pro-
     gram 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 sent to the standard out-
          put.

     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)               RISC/os Reference Manual                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 semi-
     colons 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.  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.

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)               RISC/os Reference Manual                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).

NOTES
     The bc command does not recognize the logical operators, &&
     and ||.

     The for statement must have all three expressions (E's).

     The quit statement is interpreted when read, not when exe-
     cuted.































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