NAME

       bc - arbitrary-precision arithmetic language

SYNOPSIS

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

DESCRIPTION

       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 command.

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

       Lexical

              comments are enclosed in /* */

              newlines end statements

       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)
                     function call

       Operators

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

              ++  --

              ==  <=  >=  !=  <  >

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

       Statements
              E
              { S ; ...  ; S }
              print E
              if ( E ) S
              while ( E ) S
              for ( E ; E ; E ) S
              null statement
              break
              quit
              "text"

       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.

EXAMPLE

       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)

FILES

       /lib/bclib mathematical library

SOURCE

       /src/cmd/bc.y

SEE ALSO

       dc(1), hoc(1)

BUGS

       No or operators.

       A statement must have all three

       A is interpreted when read, not when executed.

                                                                                       BC(1plan9)