


DC(1)		    UNIX Programmer's Manual		    DC(1)



NAME
     dc - desk calculator

SYNOPSIS
     dc [ file ]

DESCRIPTION
     _D_c 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.	The overall structure of _d_c 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 negative
	   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.

     s_x    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.

     l_x    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 recur-
	   sion level is popped by two.  If q is capitalized, the
	   top value on the stack is popped and the string execu-
	   tion level is popped by that value.



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DC(1)		    UNIX Programmer's Manual		    DC(1)



     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 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, division, 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 (usu-
	   ally the terminal) and executed.

     ; :   are used by _b_c for array operations.

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




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DC(1)		    UNIX Programmer's Manual		    DC(1)



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

SEE ALSO
     bc(1), which is a preprocessor for _d_c providing infix nota-
     tion and a C-like syntax which implements functions and rea-
     sonable control structures 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.





































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