unixdev.net


Switch to SpeakEasy.net DSL

The Modular Manual Browser

Home Page
Manual: (SunOS-5.10)
Page:
Section:
Apropos / Subsearch:
optional field

bc(1)                            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 op-
                erand   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



       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)



       ==   <&lt;=   >&gt;=   !=   <&lt;   >&gt;





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





   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 )

                 }

   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 sep-
       arate  statements.  Assignment to scale influences the number of digits
       to be retained on arithmetic operations in the manner  of  dc.  Assign-
       ments  to  ibase or obase set the input and output number radix respec-
       tively.

       The same letter may be used as an array, a function, and a simple vari-
       able  simultaneously.  All  variables  are  global to the program. auto
       variables are stacked during function calls. When using arrays as func-
       tion  arguments  or  defining them as automatic variables, empty square
       brackets must follow 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
       -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  state-
                       ments. 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

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

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

       or

       for (i = 1; i <&lt;= 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 success-
                                       fully.



       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 attributes:


       tab()    allbox;    cw(2.750000i)|     cw(2.750000i)     lw(2.750000i)|
       lw(2.750000i).    ATTRIBUTE   TYPEATTRIBUTE  VALUE  AvailabilitySUNWesu
       Interface StabilityStandard


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

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

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



SunOS 5.10                        29 Aug 2003                            bc(1)