I am new to this math forum, and I hope that this is an appropriate place to post this question...
I need to fit data to the "4 parameter logisitic equation" for biological relationships. Essentially the equation is the following:
y = ((A-D) / (1+ ((x/C)^B))) + D
Basically, I'll have an equally sized array of x and y values that are used to solve for variables A,B,C, and D. Right now I need to use one function from a statistical package to solve for this. I'd like to reproduce this function in the language that I am confortable with (VBA), but don't have a clue about how to approach the math! Does anyone know how to do this?!