Manual Pages for UNIX Operating System command usage for man bc

User Commands                                               bc(1)



NAME
     bc - arbitrary precision arithmetic language

SYNOPSIS
     /usr/bin/bc [-c] [-l] [file]...


     /usr/xpg6/bin/bc [-c] [-l] [file]...


DESCRIPTION
     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.

USAGE
     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 combination of
          operands and operators that evaluates to a value,


     S    Means a statement.


  Comments
     Enclosed in /* and */.

  Names (Operands)
       Simple variables: L.
       Array elements: L [ E ] (up to BC_DIM_MAX dimensions).
       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




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User Commands                                               bc(1)



     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
       while ( E ) S
       for ( E ; E ; E ) S
       null statement
       break
       quit


     .string

  Function Definitions
       define L ( L ,..., L ) {
            auto L ,..., L
            S ;... S
            return ( E )
       }





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User Commands                                               bc(1)



  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 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.

OPTIONS
     The following operands are supported:

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


  /usr/bin/bc
     -l    Defines the math functions and  initializes  scale  to
           20, instead of the default zero.


  /usr/xpg6/bin/bc




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User Commands                                               bc(1)



     -l    Defines the math functions and  initializes  scale  to
           20, instead of the default zero. All math results have
           the scale of 20.


OPERANDS
     The following operands are supported:

     file    A pathname of a  text  file  containing  bc  program
             statements.  After all cases of file have been read,
             bc reads the standard input.


EXAMPLES
     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





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User Commands                                               bc(1)



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


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




     or


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



ENVIRONMENT VARIABLES
     See environ(5) for descriptions of the following environment
     variables  that  affect  the  execution of bc: LANG, LC_ALL,
     LC_CTYPE, LC_MESSAGES, and NLSPATH.

EXIT STATUS
     The following exit values are returned:

     0              All input files were processed successfully.


     unspecified    An error occurred.


FILES
     /usr/lib/lib.b           mathematical library


     /usr/include/limits.h    to define BC_ parameters


ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:















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User Commands                                               bc(1)



     ________________________________________________________________
    |       ATTRIBUTE TYPE        |         ATTRIBUTE VALUE         |
    |_____________________________|_________________________________|
    | Availability                | system/extended-system-utilities|
    |_____________________________|_________________________________|
    | Interface Stability         | Committed                       |
    |_____________________________|_________________________________|
    | Standard                    | See standards(5).               |
    |_____________________________|_________________________________|


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

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


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



































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