BC(1plan9)                                                            BC(1plan9)

       bc - arbitrary-precision arithmetic language

       bc [ -c ] [ -l ] [ -s ] [ file ...  ]

       Bc is an interactive processor for a language that resembles C but
       provides arithmetic on numbers of arbitrary length with up to 100 digits
       right of the decimal point.  It takes input from any files given, then
       reads the standard input.  The -l argument stands for the name of an
       arbitrary precision math library.  The -s argument suppresses the
       automatic display of calculation results; all output is via the print

       The following syntax for bc programs is like that of C; L means letter a-
       z, E means expression, S means statement.


              comments are enclosed in /* */

              newlines end statements


              simple variables: L
              array elements: L[E]
              The words ibase, obase, and scale

       Other operands

              arbitrarily long numbers with optional sign and decimal point.



                     number of significant decimal digits

                     number of digits right of decimal point

                     function call


              +  -  *  /  %  ^  (% is remainder; ^ is power)

              ++  --

              ==  <=  >=  !=  <  >

              =  +=  -=  *=  /=  %=  ^=

              { S ; ...  ; S }
              print E
              if ( E ) S
              while ( E ) S
              for ( E ; E ; E ) S
              null statement

       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 an expression at the top level is printed unless the main
       operator is an assignment or the -s command line argument is given.  Text
       in quotes, which may include newlines, is always printed.  Either
       semicolons or newlines 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.
       Automatic variables are pushed down during function calls.  In a
       declaration of an array as a function argument or automatic variable
       empty square brackets must follow the array name.

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

       Define a function to compute an approximate value of the exponential.
       Use it to print 10 values.  (The exponential function in the library
       gives better answers.)

       scale = 20
       define e(x) {
            auto a, b, c, i, s
            a = 1
            b = 1
            s = 1
            for(i=1; 1; i++) {
                 a *= x
                 b *= i
                 c = a/b
                 if(c == 0) return s
                 s += c
       for(i=1; i<=10; i++) print e(i)

       /lib/bclib mathematical library


       dc(1), hoc(1)

       No or operators.

       A statement must have all three

       A is interpreted when read, not when executed.