BC(I) 2/20/75 BC(I)





BC(I)                        2/20/75                        BC(I)







NAME

     bc - arbitrary precision interactive language



SYNOPSIS

     bc [ -l ] [ file ... ]



DESCRIPTION

     Bc  is  an  interactive  processor  for  a  language   which

     resembles C but provides unlimited precision arithmetic.  It

     takes input from any files given, then  reads  the  standard

     input.   The  `-l' argument stands for the name of a library

     of mathematical subroutines which contains sine (named `s'),

     cosine (`c'), arctangent (`a'), natural logarithm (`l'), and

     exponential  (`e').   The  syntax  for  bc  programs  is  as

     follows; E means expression, S means statement.



     Comments

           are enclosed in /* and */.



     Names

           letters a-z

           array elements: letter[E]

           The words `ibase', `obase', and `scale'



     Other operands

           arbitrarily  long  numbers  with  optional  sign   and

           decimal point.

           ( E )

           sqrt ( E )

           <letter> ( E , ... , E )



     Operators

           +  -  *  /  %  ^

           ++   --         (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 are exemplified by

           define <letter> ( <letter> ,..., <letter> ) {

                  auto <letter>, ... , <letter>

                  S; ... S

                  return ( E )

           }



     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

     semicolons or newlines may separate statements.   Assignment

     to  scale  influences the number of digits to be retained on

     arithmetic operations.  Assignments to ibase  or  obase  set

     the input and output number radix respectively.



     The same letter may be used as an  array  name,  a  function

     name,   and   a   simple  variable  simultaneously.   `Auto'

     variables are saved and restored during function calls.  All

     other  variables  are  global  to  the  program.  When using

     arrays as function arguments or defining them  as  automatic

     variables empty square brackets must follow the array name.



     For 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

             }

     }



     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



SEE ALSO

     dc (I), C Reference Manual, ``BC -  An  Arbitrary  Precision

     Desk-Calculator Language.''



BUGS

     No &&, | | yet.

     for statement must have all three E's

     quit is interpreted when read, not when executed.
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