Differences between revisions 7 and 8
⇤ ← Revision 7 as of 2009-03-14 19:23:58 →
Size: 2764
Editor: BurcinErocal
Comment: add feature requests from ncalexan
← Revision 8 as of 2009-03-15 19:16:10 → ⇥
Size: 2782
Editor: BurcinErocal
Comment: move better latex names for symbols and symbolic vectors and matrices to done
Deletions are marked like this. Additions are marked like this.
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 * better latex output, copy symbol latex code from current SR
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 * symbolic matrices, vectors
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 * better latex output for symbol names, use sage.misc.latex.latex_variable_name
 * symbolic matrices, vectors

TODO list for the pynac interface

"fully get rid of maxima-based symbolic variables"

remaining items

  • support for _fast_eval
  • hash is random
  • pyobject deallocations, memory leaks
  • noncommutative symbols
  • symbol domains (ginac supports real, complex, integer)
  • precision for numeric evaluation (evalf, _mpfr_, William's list) 

genuine coercions to real field, etc.
  • pickling (William's list) 

Support pickle via the "archive" print mode.
  • gcd (William's list) 

Maybe change SAGE's Ginac to make a call to a cython gcd function, then use
singular, since singular's gcd over QQ is much better than ginac's, I think,
and ginac *only* does GCD over QQ.  Actually, just make everything in normal.cpp
be implemented via Singular, probably...
  • unevaluated expressions?
  • configurable printing for symbolic functions
  • ability to change how partial derivatives are printed
  • piecewise expressions, substitution and pattern matching

long term

  • find a better scheme for handling compare()

in progress

  • Arithmetic with infinity (almost done)
  • Series expansions

done

  • 1/gamma(-1) = 0
  • better latex output for symbol names, use sage.misc.latex.latex_variable_name
  • symbolic matrices, vectors

Sage 3.3 - pynac-0.1.2

  • symbolic binomial and factorial
  • iterator for sage.symbolic.expression.Expression
  • operator method
    • (similar to current _operator(), but returns the function if the expression is a function application) 

sage: var('x,y,z,n,i,j',ns=1)
(x, y, z, n, i, j)
sage: sin(x).operator()
sin
sage: type(sin(x).operator())
<class 'sage.calculus.calculus.Function_sin'>
sage: factorial(n).operator()
factorial
sage: type(factorial(n).operator())
<class 'sage.calculus.calculus.Function_factorial'>
  • evaluation
    • Substitution for more than variable done, call semantics/syntax needs more thought
  • print order (William's list) 

This text was a part of William's original todo notes, perhaps now it's confusing to include it here.

Now,
sage: x^2 + x^4 + x^3
x^2 + x^3 + x^4
sage: a^3*x^10 + x^12 - a^15
x^12 + a^3*x^10 - a^15
So it is printing from lowest to highest degree, like mathematica (or power series),
but unlike the standard sage convention (or maple, singular, MATH, etc.):
sage: R.<a,x> = QQ[]
sage: a^3*x^10 + x^12 - a^15
-a^15 + a^3*x^10 + x^12
sage: singular(a^3*x^10 + x^12 - a^15)
-a^15+a^3*x^10+x^12
  • collect_common_factors (William's list) 

need to be able to do this (from ginsh):
> collect_common_factors(x/(x^2 + x));
(1+x)^(-1)
  • pretty printing (latex() method, a/b instead of a*b^{-1}, etc.)
  • callable symbolic expressions