bc(1)                    USER COMMANDS                      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, which it invokes automatically unless the -c option
     is  present.  In this case the dc input is sent to the stan-
     dard 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



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bc(1)                    USER COMMANDS                      bc(1)



           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.

     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)                    USER COMMANDS                      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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