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dc - desk calculator - rpn

DESCRIPTION
     It's a stack calculator using Reverse Polish Notation.  Values are pushed
     into a stack and operations pop values from the stack in reverse order.

   Example
     To get the result of 1 + 2:
     1 2 + f
     3
     1.	  1 is pushed into the stack.
     2.	  2 is pushed into the stack.
     3.	  + pops the top two values from the stack, adds them and the result
	  is pushed into the stack.
     4.	  f prints the complete stack.

   Another example
     To get the result of 2 * 3 + 4:
     -	 one way to do it:
	 2 3 * 4 + f
	 10
	       + pops 4 and *, therefore * pops 2 and 3, multiplies them and 6
	       is sent into the stack resulting in 6 4 +.
     -	 another way to do it:
	 4 2 3 * + f
	 10
	       + pops * which pops 2 and 3 to get 6 which is pushed into the
	       stack resulting in 4 6 +.

   Scripting
     dc can be called with file: dc filename

OPERATIONS
     The common operation are supported: + - * / ^.

     %	    | pops the top two values, divides the second popped value by the
	    first one and pushes the remainder into the stack. Eg.: 8 4 % fc
	    0, 8 5 % fc 3.
     ~	    | similar but returns the quotient and remainder: 8 4 ~ fc 0 2, 8
	    5 ~ fc 3 1
     v	    | pops the top value off the stack and calculates the square root.

PRINTING
     f	    | prints stack.
     p	    | prints value on top of the stack with newline.
     n	    | prints value on top of the stack without newline.

STACK
     c	    | clears the stack.
     r	    | swap the top two values of the stack.
     d	    | duplicates value on top of the stack.

REGISTERS
     sr	    | pops the top value off the stack and stores it into the register
	    r. (r can be any single character)
     Sr	    | same as s but overwrites the original value of the register.
     lr	    | loads a copy of the value of register r.
     Lr	    | loads the value of register r removing it from the register.

PARAMETERS
     k	    | pop the top value off the stack and use it as the precision
	    parameter.

STRINGS
     Strings can be stored as [string], this can be used to store strings or
     operations as macros which can be saved as a macro.

   Example
     [the string]p
     the string
     [2 2 +]Sa
     laxp
     4

   Macros
     Macros can be invoked based on conditions:

     >r	    | compare the top two values of the stack and runs r if the top
	    value of the stack is greater.
     !>r    | similar but runs r if the top value is not greater. (less or
	    equal)
     <r	    | runs r if the top value is lower than the seconf value..
     !<r    | runs r if the top value is not lower than the second value.
	    (greater or equal)
     =r	    | runs r if the top two values of the stack are equal.
     !=r    | runs r if the top two values of the stack are not equal.
     Examples:

     Considering the top two values 1 2, r could run with the following
     comparisons: >r, !<r, !=r.	 r will not run with the following
     comparisons: !>r, <r, =r.

     [runs]Sa
     [lap]Sb
     1 2 >b
     runs
     1 2 !>b
     1 2 <b
     1 2 !<b
     runs
     1 2 =b
     1 2 !=b
     runs

SEE ALSO
     - OpenBSD manpages: dc(1)

AUTHORS
     ohazot(oh) | about(oh) | ohazot.com: https://ohazot.com
     <admin@ohazot.com>

OpenBSD , linux |   Created:2025-10-15|Updated:2025-10-15|		DC(oh)