DC(1-SysV)          RISC/os Reference Manual           DC(1-SysV)



NAME
     dc - desk calculator

SYNOPSIS
     dc [ file ]

DESCRIPTION
     dc is an arbitrary precision arithmetic package.  Ordinarily
     it operates on decimal integers, but one may specify an
     input base, output base, and a number of fractional digits
     to be maintained.  (See bc(1), a preprocessor for dc that
     provides infix notation and a C-like syntax that implements
     functions.  Bc also provides reasonable control structures
     for programs.)  The overall structure of dc is a stacking
     (reverse Polish) calculator.  If an argument is given, input
     is taken from that file until its end, then from the stan-
     dard input.  The following constructions are recognized:

     number
           The value of the number is pushed on the stack.  A
           number is an unbroken string of the digits 0-9.  It
           may be preceded by an underscore () to input a nega-
           tive number.  Numbers may contain decimal points.

     + - / * % ^
           The top two values on the stack are added (+), sub-
           tracted (-), multiplied (*), divided (/), remaindered
           (%), or exponentiated (^).  The two entries are popped
           off the stack; the result is pushed on the stack in
           their place.  Any fractional part of an exponent is
           ignored.

     sx    The top of the stack is popped and stored into a
           register named x, where x may be any character.  If
           the s is capitalized, x is treated as a stack and the
           value is pushed on it.

     lx    The value in register x is pushed on the stack.  The
           register x is not altered.  All registers start with
           zero value.  If the l is capitalized, register x is
           treated as a stack and its top value is popped onto
           the main stack.

     d     The top value on the stack is duplicated.

     p     The top value on the stack is printed.  The top value
           remains unchanged.

     P     Interprets the top of the stack as an ASCII string,
           removes it, and prints it.

     f     All values on the stack are printed.



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     q     Exits the program.  If executing a string, the recur-
           sion level is popped by two.

     Q     Exits the program.  The top value on the stack is
           popped and the string execution level is popped by
           that value.

     x     Treats the top element of the stack as a character
           string and executes it as a string of dc commands.

     X     Replaces the number on the top of the stack with its
           scale factor.

     [ ... ]
           Puts the bracketed ASCII string onto the top of the
           stack.

     <x   >x   =x
           The top two elements of the stack are popped and com-
           pared.  Register x is evaluated if they obey the
           stated relation.

     v     Replaces the top element on the stack by its square
           root.  Any existing fractional part of the argument is
           taken into account, but otherwise the scale factor is
           ignored.

     !     Interprets the rest of the line as a UNIX system com-
           mand.

     c     All values on the stack are popped.

     i     The top value on the stack is popped and used as the
           number radix for further input.

     I     Pushes the input base on the top of the stack.

     o     The top value on the stack is popped and used as the
           number radix for further output.

     O     Pushes the output base on the top of the stack.

     k     The top of the stack is popped, and that value is used
           as a non-negative scale factor:  the appropriate
           number of places are printed on output, and maintained
           during multiplication, division, and exponentiation.
           The interaction of scale factor, input base, and out-
           put base will be reasonable if all are changed
           together.

     z     The stack level is pushed onto the stack.




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     Z     Replaces the number on the top of the stack with its
           length.

     ?     A line of input is taken from the input source (usu-
           ally the terminal) and executed.

     ; :   are used by bc(1) for array operations.

EXAMPLE
     This example prints the first ten values of n!:

        [la1+dsa*pla10>y]sy
        0sa1
        lyx

SEE ALSO
     bc(1).

DIAGNOSTICS
     x is unimplemented
          where x is an octal number.

     stack empty
          for not enough elements on the stack to do what was
          asked.

     Out of space
          when the free list is exhausted (too many digits).

     Out of headers
          for too many numbers being kept around.

     Out of pushdown
          for too many items on the stack.

     Nesting Depth
          for too many levels of nested execution.


















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