Hi Louis,
Same answer for float, complex or big numbers?
Floats will be just a matter of adjusting the regexes. Divisions that give floats are left as fractions by defautl for now.
Complex numbers are not yet implemented, but PEAR's Math_Complex package should do most of the job. Ditto for big numbers w/ PHP's BC extension.
The algebra depends on the groups or body.
Can we factorize the most
as Exp = a + X.(b + X.(c + X.(...)))
or as Exp = (a + X).(b +X).(c +X) ...
I'm not sure what you mean here, but I can tell you the first way will work and the second is not yet implemented (parentheses * or / parentheses)
So far it's given variables X and Y
how is the expression factorized ?
X first: X^3*Y^2
or Y first: Y^2*X^3 ?)
Following alphabetical order, then descending order of the powers. I'll have to implement/find a real sorting algorithm for multi-variable terms, i.e. xyz comes before xy because xyz is x^1y^1z^1 and xy is x^1y^1z^0
How are the features stored ? (not XML ???)
Right now the class offers two ways of output: text and HTML. There is also an option to output to MathML, but it uses an external class (http://www.jcphysics.com/ASCIIMath/), and there should be a separate PEAR package built for this class.
What is the notation ?
For HTML output the powers and fractions are formatted with the <sup> and <sub> elements. For text output, the notation is the same as PHP's (plus the exponent operator, which is the caret [^]).
Some computed algebras exist,
PHP & Pear allmost give access to such oriented systems.
Wheels are allready invented here,
Better make a PHP/Pear 4WD car,
a wheel in each algebra system existing.
I already use the Math_Fraction package for fractions, and as stated above I'll probably be using the Math_Complex and the BC extension very soon. I cannot see what else PEAR or PHP could provide me that would be useful in building this ?
Happy new year,
- Louis