DC(I)                        1/15/73                        DC(I)







NAME

     dc - desk calculator



SYNOPSIS

     dc [ file ]



DESCRIPTION

     Dc is an arbitrary  precision  integer  arithmetic  package.

     The  overall  structure of dc is a stacking (reverse Polish)

     calculator.  The following constructions are  recognized  by

     the calculator:



     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.



     + - * / % ^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.



     sx         The top of the stack is popped and stored into  a

               register named x, where x may be any character.



     lx         The value in register x is pushed on  the  stack.

               The  register  x  is  not  altered.  All registers

               start with zero value.



     d          The top value on  the  stack  is  pushed  on  the

               stack.  Thus the top value is duplicated.



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

               value remains unchanged.



     f          All values on the  stack  and  in  registers  are

               printed.



     q          exits the program. If  executing  a  string,  the

               nesting level is popped by two.



     x          treats  the  top  element  of  the  stack  as   a

               character string and executes it as a string of dc

               commands.



     [ ... ]    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.  Register x is executed if they obey the

               stated relation.



     v          replaces the top element  on  the  stack  by  its

               square root.



     !          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.



     o          The top value on the stack is popped and used  as

               the number radix for further output.



     z          The stack level is pushed onto the stack.



     ?          A line of input is taken from  the  input  source

               (usually the console) and executed.



     new-line   ignored except as the name of a  register  or  to

               end the response to a ?.



     space      ignored except as the name of a  register  or  to

               terminate a number.



     If a file name is given, input is taken from that file until

     end-of-file,  then  input  is  taken  from  the console.  An

     example which prints the first ten values of n! is



        [la1+dsa*pla10>x]sx

        0sa1

        lxx





FILES

     /etc/msh   to implement `!'



DIAGNOSTICS

     (x) ? for unrecognized character x.

     (x) ? for not enough elements on the stack to  do  what  was

     asked by command x.

     `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.



BUGS