CAS simplifying non-zero expressions to 0

[parisse]

Nick: Ok, take something else if you think you will find elsewhere. That will not change the fact that rewriting your large expression as a rational fraction (that's what simplify does, and perhaps that's what you misunderstood) will return a big answer. If you need to plot this |Z|, writing it as a rational fraction is a bad idea, you should keep it as is (I wonder what kind of simplification you expected by the way). This is not my CAS versus other CAS, it's math. And by the way, Xcas has a fast kernel for polynomial/rational fraction computations (comparable to the best CAS).

Nigel: Solving 6.63e-34 x f = E should ideally be done via solve(h*f=E,f) then replace h and E by their values or with fsolve (E replaced by it's numerical value). I'll have a look for solve(6.63e-34*f = E,f) but improving the exact solver is certainly difficult (not for linear equations of course, but for more complicated equations, symbolic solving does not use the same kind of algorithms than numeric solving).