Inverse function

ROOT
1

Hello,

Could you help me with this one.
I have some complicated function z=f(x,y). I need to get x=g(z,y).
Can I do this in root?

2

yes you can do by using for example

TF1::GetX, see root.cern.ch/root/htmldoc/TF1.html#TF1:GetX

and use y as a parameter of the function.
Alternativly you can use also the root finder algorithms from MathMore,
there you need to find the roots for the function h(x) = f(x,y)-z
There you have algorithms which can use the function derivatives and be in some cases more efficient.
They are documented at

seal.web.cern.ch/seal/MathLibs/5 … nders.html

and an example program is available in CVS at

root.cern.ch/viewcvs/mathmore/te … cvs-markup

Best Regards,

Lorenzo

3

Thank you so much! Appreciate it.