# How to use inverse function of Cp vs Lambda of wind turbine in MATLAB script

I want to use inverse function. I know the value of Cp and I need to calculate Lamda and Beta through this formula. How can I do?

I think it has to do with a lookup table of Cp vs Lambda for DFIG Wind Turbine in MATLAB script format. Equation of Cp vs Lambda is attached herewith.

• that looks not like a lookup table, but is plain a mathematical formula that you can just type down in a matlab function - done. Mar 3, 2022 at 20:09
• this is a function, not something that's part of a lookup table, so what exactly are you planning to do? It's really not clear what you want to look up, by what. (and the generator has nothing to do with this, really?) (also unclear why, as this is a rather handy function that's not very well-mannered, so any discretization would be very unwieldy, and probably slower than direct calculation. Make sure you're actually solving a problem, not creating one) Mar 3, 2022 at 20:14
• Are you trying to find an inverse function? Lookup table seems like a very bad way to evaluate a function that has fairly low computational cost. Especially one with two variables. I can't imagine speed is very important in a wind turbine application. Mar 3, 2022 at 20:46
• @SpehroPefhany Yes I want to use inverse function. I know the value of Cp and I need to calculate Lamda and Beta through this formula. How can I do? Mar 4, 2022 at 2:25
• If you only know Cp there will be one or two infinite sets of solutions (or possibly none) depending on how the plane of Cp = x cuts the 3D surface. You need at least one other variable to get an answer (might be zero, one or two answers it looks like). See this representation of the surface: i.imgur.com/nHnKlid.png Mar 4, 2022 at 2:58