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realease 1.00
- renamed commandline tool to rpnc - added better README - added collector mode - added V command - added R command
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Thomas von Dein
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README.md
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README.md
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## Reverse Polish Notation Calculator for the commandline
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This is a small commandline calculator which takes its input in
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[https://en.wikipedia.org/wiki/Reverse_Polish_notation](reverse polish notation)
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form.
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It has an unlimited stack, supports various stack manipulation
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commands, can be used interactively or via a pipe and has a collector
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mode. It doesn't have any other dependencies than Perl.
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## Usage
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Calculate the summary resistance of parallel resistors with 220, 330
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and 440 Ohm using the following formula:
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1 / (1/R1 + 1/R2 + 1/R3)
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Here's the sample session:
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0 % 1
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stack 1: 1
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1 % 1
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stack 2: 1
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stack 1: 1
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2 % 220
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stack 3: 1
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stack 2: 1
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stack 1: 220
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3 % /
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stack 2: 1
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stack 1: 0.00454545454545455
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=> 0.00454545454545455
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2 % 1
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stack 3: 1
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stack 2: 0.00454545454545455
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stack 1: 1
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3 % 330
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stack 4: 1
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stack 3: 0.00454545454545455
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stack 2: 1
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stack 1: 330
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4 % /
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stack 3: 1
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stack 2: 0.00454545454545455
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stack 1: 0.00303030303030303
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=> 0.00303030303030303
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3 % 1
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stack 4: 1
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stack 3: 0.00454545454545455
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stack 2: 0.00303030303030303
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stack 1: 1
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4 % 440
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stack 5: 1
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stack 4: 0.00454545454545455
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stack 3: 0.00303030303030303
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stack 2: 1
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stack 1: 440
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5 % /
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stack 4: 1
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stack 3: 0.00454545454545455
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stack 2: 0.00303030303030303
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stack 1: 0.00227272727272727
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=> 0.00227272727272727
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4 % +
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stack 3: 1
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stack 2: 0.00454545454545455
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stack 1: 0.0053030303030303
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=> 0.0053030303030303
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3 % +
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stack 2: 1
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stack 1: 0.00984848484848485
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=> 0.00984848484848485
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2 % /
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stack 1: 101.538461538462
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=> 101.538461538462
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The *%* character denotes the interactive prompt. What we basically entered was:
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1 1 220 / 1 330 / 1 440 / + + /
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Which translates to:
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1 ((1 / 220) + (1 / 330) + (1 / 440))
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So, you're entering the numbers and operators as you would do on
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paper. To learn more, refer to the Wikipedia page linked above.
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## Collector mode
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Beside traditional RPN you can also enter a special mode, called
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*collector mode* by entering the <kbd>(</kbd> command. The collector
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mode has its own stack (a sub stack) which is independed of the
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primary stack. Inside this mode you can use all operators, however
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they work on *ALL* items on the sub stack.
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So, let's compare. If you had in normal RPN mode the following stack:
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3
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5
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6
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and then entering the <kbd>+</kbd> operator, the calculator would pop
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5 and 6 from the stack, add them and push the result 11 back to the
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stack.
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However, if you are in collector mode with this stack, then all the
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items would be added, the sub stack would be cleared and the result 14
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would be added to the primary stack.
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You will leave the collector mode after an operator has been
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executed. But you can also just leave the collector mode with the
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command <kbd>)</kbd> leaving the sub stack intact. That is, upon
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re-entering collector mode at a later time, you'll find the unaltered
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sub stack of before.
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## Undo
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Every operation which modifies the stack can be reversed by entering
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the <kbd>u</kbd> command. There's only one level of undo and no redo.
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## Using STDIN via a PIPE
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If the commandline includes any operator, commands will be read from
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STDIN, the result will be printed to STDOUT wihout any decoration and
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the program will exit. Commands can be separated by whitespace or
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newline.
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Examples:
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echo "2 2" | rpnc +
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(echo 2; echo 2) | rpnc +
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Both commands will print 4 to STDOUT.
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## Complete list of all supported commands:
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* <kbd>c</kbd> clear stack
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* <kbd>s</kbd> show the stack
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* <kbd>d</kbd> toggle debugging (current setting: 0)
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* <kbd>r</kbd> reverse the stack
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* <kbd>R</kbd> rotate the stack
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* <kbd>(</kbd> enter collect mode
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* <kbd>)</kbd> leave collect mode
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* <kbd>u</kbd> undo last operation
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* <kbd>q</kbd> finish (<kbd>C-d</kbd> works as well)
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* <kbd>?</kbd> print help
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## Supported mathematical operators:
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* <kbd>+</kbd> add
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* <kbd>-</kbd> substract
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* <kbd>/</kbd> divide
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* <kbd>*</kbd> multiply
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* <kbd>^</kbd> expotentiate
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* <kbd>%</kbd> percent
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* <kbd>&</kbd> bitwise AND
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* <kbd>|</kbd> bitwise OR
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* <kbd>x</kbd> bitwise XOR
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* <kbd>V</kbd> pull root (2nd if stack==1)
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## Copyleft
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Copyleft (L) 2019 - Thomas von Dein.
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Licensed under the terms of the GPL 3.0.
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