pythonica is a proof of concept python implementation of a symbolic math program, based upon the Mathematica style syntax.
pythonica parses Mathematica style input into a canonical expression form known as "FullForm". The expression is then evaluated, generating a result. The result is simplified as much as the program is able, then printed to the user -- both in FullForm, and in "natural" form. (The intermediate steps are displayed to make it more apparent what is happening; minor changes to the code could surpress this intermediate output.)
For an expanded description, see: http://www.strout.net/info/coding/python/pythonica.html
- Joe Strout - original author.
- Kevin Ballard - second maintainer; additional modifications as described in the Changes section.
pythonica is public domain. Do with it as you like.
These are the changes that Kevin Ballard completed on top of the original Joe Strout codebase.
- Added list support. Lists are encased in square brackets ([])
- Added slice support. A slice is written as [[args]] right after an expression and returns the component of the expression described by args. The first arg acts on the expression, the second arg acts on the result of the first, etc. A value of 0 returns a symbol for the head of the expression, a positive integer returns that component of the expression (as if the expression was a 1-based list) and a negative number returns the component that number from the end of the expression.
- Fixed parsing such that a+bc+d works and that a=cd+k*r works
- Fixed complex number parsing such that j by itself is equivalent to 1j
- Fixed floating point numbers to not complain that "." isn't an operator
- Complex number shorthand now works! 2j now becomes Complex[0,2], and 2+2j now becomes Plus[2,Complex[0,2]]
- Number detection is now better. Instead of saying "Syntax error" if you type an invalid token that begins with a digit, it now tells you specifically that symbols can't begin with a digit
- Added functions Sqrt/Root/Exp/Abs/Mod/Round
- Re-wrote a bunch of logic concerning parsing tokens and groups
- Fixed some strange bugs, like Sin[3,2],2 becoming Sin[3,2,2]
- Made non-alphanumeric chars treated as operators
- Added an undefined operator message for undefined operators
- Added fairly comprehensive complex number support - currently you have to write complex numbers as Complex[real,imag] (imag being optional and defaults to 0). In the future you will be able to write them like (3+2j)
- Added functions Sin/Cos/Tan/ASin/ACos/ATan/Rad2Deg/Deg2Rad
- Divide is no longer chainable
- You can put full-form functions next to each other and it assumes multiply: Sin[3]Sin[4] is equivalent to Sin[3]*Sin[4]
- If an exception occurs while running as a program, it outputs information and continues. If an exception occurs while running from the interpreter (i.e. imported as a module) it passes the exception on for debugging
- Other miscellaneous bugfixes