Op 19-apr-2008, om 18:58 heeft [EMAIL PROTECTED] het volgende geschreven: > Issue 93: Square root denesting > http://code.google.com/p/sympy/issues/detail?id=93 > > Comment #11 by kirill.smelkov: > At present we have sqrtdenest written by David: > > In [1]: sqrtdenest(sqrt(14+4*sqrt(6))) > Out[1]: > ⎽⎽⎽ ⎽⎽⎽ > ╲╱ 2 + 2*╲╱ 3 > > > Jurjen, David, All, > > What is the state of this issue? Interesting you ask. There is a "sqrtdenest" function, which implements an article that has a nice theoretical approach to denesting, but omits a few important details. I've been struggling with the theory, and I am a few weeks from a brand new implementation that is more understandable, more flexible, and faster. The short idea is: If you denest sqrt(a+b), a and/or b has sqrts in it, you first denest sqrt(a**2-b**2), and if that denests to d, write sqrt(a+b) as sqrt((a+d)/2)+-sqrt((a-d)/2) the sign is equal to the sign of b. The interesting challenges are: - split the expression below the sqrt into the proper a and b (I am quite far with that, while the original article lacks about all information on how to do this) - find the sign of b (sometimes not so easy, but I'll work this out, I guess) - extrapolate for expressions that are not Numbers (work in progress). - Jurjen
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