4.3BSD - /usr/man/cat1/dc.0

DC(1)                                                                    DC(1)


NAME
       dc - desk calculator

SYNOPSIS
       dc [ file ]

DESCRIPTION
       Dc  is  an arbitrary precision arithmetic package.  Ordinarily it oper‐
       ates on decimal integers, but one may specify  an  input  base,  output
       base,  and a number of fractional digits to be maintained.  The overall
       structure of dc is a stacking (reverse Polish) calculator.  If an argu‐
       ment  is  given, input is taken from that file until its end, then from
       the standard 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 negative  number.   Numbers  may  contain
             decimal points.

       +  - /  *  %  ^
             The  top  two  values on the stack are added (+), subtracted (-),
             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 and in registers are printed.

       q     exits the program.  If executing a string, the recursion level is
             popped  by  two.  If q is capitalized, 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  fac‐
             tor.

       [ ... ]
             puts the bracketed ascii string onto the top of the stack.

       <x  >x  =x
             The  top two elements of the stack are popped and compared.  Reg‐
             ister x is executed 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 command.

       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, divi‐
             sion, and exponentiation.  The interaction of scale factor, input
             base,  and  output  base  will  be  reasonable if all are changed
             together.

       z     The stack level is pushed onto the stack.

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

       ?     A line of input is taken from the input source (usually the  ter‐
             minal) and executed.

       ; :   are used by bc for array operations.

       An example which prints the first ten values of n! is

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

SEE ALSO
       bc(1), which is a preprocessor for dc providing infix notation and a C-
       like syntax which implements functions and  reasonable  control  struc‐
       tures for programs.

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.


7th Edition                     April 29, 1985                           DC(1)