days6/sprint/calculus

Things to improve:

• pattern matching
• subexpression substitution
• unifying and especially simplify the way to check the type of an
  • expression. Now you need to do this ugly switch:

def _is(e, what):

• import operator if what == "Mul":

  • return isinstance(e, sage.calculus.calculus.SymbolicArithmetic) and \

    • e._operator == operator.mul
  if what == "Add":

  • return isinstance(e, sage.calculus.calculus.SymbolicArithmetic) and \

    • e._operator == operator.add
  if what == "Pow":

  • return isinstance(e, sage.calculus.calculus.SymbolicArithmetic) and \

    • e._operator == operator.pow
  if what == "Div":

  • return isinstance(e, sage.calculus.calculus.SymbolicArithmetic) and \

    • e._operator == operator.div
  if what == "log":

  • return isinstance(e, sage.calculus.calculus.SymbolicComposition) and \

    • bool(e._operands[0] == sage.all.log)
  if what == "exp":

  • return isinstance(e, sage.calculus.calculus.SymbolicComposition) and \

    • bool(e._operands[0] == sage.all.exp)
  if what == "Function":

  • return isinstance(e, sage.calculus.calculus.SymbolicComposition)

  elif what == "Rational":
  • return isinstance(e, sage.rings.rational.Rational)
  elif what == "Real":

  • return isinstance(e, sage.rings.real_mpfr.RealNumber)

  else:
  • raise "Sorry, unknown 'class': %s" % what

Those are just things I discovered when trying to port the limits from SymPy to SAGE. Then there are other things, for example:

• working with unknown functions, expanding them in series, etc.

(there is some trac ticket for that already)