bc - arbitrary precision arithmetic language


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


     The bc utility implements an arbitrary precision calculator.
     It  takes  input  from  any files given, then reads from the
     standard input. If the standard input and standard output to
     bc  are  attached  to  a  terminal,  the invocation of bc is
     interactive, causing behavioral constraints described in the
     following sections. bc processes a language that resembles C
     and is a preprocessor for the desk  calculator  program  dc,
     which  it  invokes  automatically  unless  the  -c option is
     specified. In this case the dc input is sent to the standard
     output instead.


     The syntax for  bc programs is as follows:

     L     means a letter a-z,

     E     means  an  expression:  a  (mathematical  or  logical)
           value,  an  operand  that takes a value, or a combina-
           tion of operands and operators  that  evaluates  to  a

     S     means a statement.

          Enclosed in /* and */.

  Names (Operands)
               Simple variables: L.

               Array elements: L [ E ] (up to  BC_DIM_MAX  dimen-

               The words ibase, obase (limited  to  BC_BASE_MAX),
               and scale (limited to BC_SCALE_MAX).

  Other Operands
     Arbitrarily long numbers  with  optional  sign  and  decimal
     point.  Strings  of  fewer  than  BC_STRING_MAX  characters,
     between double quotes ("). ( E )

     sqrt ( E )
           Square root

     length ( E )
           Number of significant decimal digits.

     scale ( E )
           Number of digits right of decimal point.

     L ( E , ... , E )

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

     ++   --
           (prefix and postfix; apply to names)

     ==   <=   >=   !=   <   >

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


               { S ;... ; S }

               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

           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 semicolons
     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 respectively.

     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  stacked  during  function
     calls.  When  using arrays as function arguments or defining
     them as automatic variables, empty square brackets must fol-
     low the array name.


     The following operands are supported:

     -c    Compile only. The output is dc commands that are  sent
           to the  standard output.

     -l    Define the math functions and initialize  scale to 20,
           instead of the default zero.


     The following operands are supported:

     file  A pathname of a text file containing bc program state-
           ments. After all cases of file have been read, bc will
           read the standard input.


     Example 1: Setting the precision of a variable

     In the shell, the following assigns an approximation of  the
     first ten digits of n to the variable x:

     x=$(printf "%s\n" 'scale = 10; 104348/33215' | bc)

     Example 2: Defining a computing function

     Defines a function to compute an approximate  value  of  the
     exponential function:

     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

     Example 3: Printing the approximate values of the function

     Prints approximate values of the exponential function of the
     first ten integers:

     for(i=1; i<=10; i++) e(i)


     for (i = 1; i <= 10; ++i) {         e(i) }


     See environ(5) for descriptions of the following environment
     variables  that  affect  the  execution of bc: LANG, LC_ALL,


     The following exit values are returned:

     0     All input files were processed successfully.

           An error occurred.


           mathematical library

           to define BC_ parameters


     See attributes(5) for descriptions of the  following  attri-
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    | Availability                | SUNWesu                     |
    | Interface Stability         | Standard                    |


     dc(1), awk(1), attributes(5), environ(5), standards(5)


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

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

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