Reverse Polish Notation

`dc` is an arbitrary precision reverse Polish notation Unix command line calculator. It lacks transcendental functions.

**Stack operators:**

stack effect | dc | hp-11c | forth | factor | postscript |
---|---|---|---|---|---|

( - ) | p | top of stack always in display |
dup . | dup . | |

(a - ) | n | none |
. | . | pop |

(a b - b a) | r | x≷y | swap | swap | exch |

(a - a a) | d | ENTER | dup | dup | dup |

c | none |
clearstack | clear | clear | |

(a b c d - d a b c) | R↓ | USE: shuffle -roll |
|||

(a b c d - b c d a) | R↑ | 3 roll | USE: shuffle roll |
4 -1 roll |

`gforth` has separate integer and float stacks. I don't know how to take an integer, convert it to float, and put it on the float stack.

The `gforth` float operators have the same names as the integer operators with an "f" prefix.

`gforth` floats must always be entered using scientific notation:

```
$ gforth
Gforth 0.7.3, Copyright (C) 1995-2008 Free Software Foundation, Inc.
Gforth comes with ABSOLUTELY NO WARRANTY; for details type `license'
Type `bye' to exit
3.14e0 fexp f. 23.1038668587222 ok
bye
```

Factor can be run from the command line. It has a surprisingly large standard library.

If Factor is installed on a Mac, one can put it in the search `PATH`:

`ln -s /Applications/factor/factor /usr/local/bin/factor`

On a Linux system, one may find that there is already a `factor` command which performs prime factorization.

page revision: 5, last edited: 18 Jul 2017 14:55