Landau Calculator
This application performs basic arithmetic on small positive natural numbers using the abstract formulae derived by Landau in his Foundations of Analysis. It can use any arbitrary set of symbols as its "numbers" — you may select below "numbers" (the Arabic numbers); "words" ("one + two = three" and so forth); or "fruit" (pineapple + cantaloupe = tomato; this form is just as valid as any other in Landau's system and involves no conversion to numerals).
The calculator currently supports only succession (a ' sign after the number symbol), addition, and multiplication, but in performing these operations it will show you every step it is performing along the way. It does support parentheses and will use the standard order of operations. It supports numbers up to 100 in numbers mode, up to "twenty-five" in words mode, and the following symbols in fruit mode:
apple, pear, pineapple, tangerine, plum, peach, cantaloupe, banana, orange, tomato, cherry, raspberry, grapefruit, mango, cranberry, strawberry, apricot, grape, watermelon, boysenberry, kiwi, guava, pomegranate, eggplant, quince, greengage, nectarine, persimmon, durian, lime, crabapple, lemon.
Source Code
The source code (in Python) to the Landau calculator is available under the BSD License. The source is a package (landau.py) which can be used in a CGI application, as here, or in other applications.
Landau Source [ZIP]
