Please help on curve fitting

I need to fit my data sets to an equation Y = A + Bx^2 + C D^4. With my limited knowledge, I have tried p=polyfit(x,y,4); which returned with values for coefficients of x and x^3 terms. Would really apprecite any help.

Thank you

Answer 1

[John D'Errico]

Assuming that you mean a model of the form

Y = A + Bx^2 + C x^4

Simple is to download my polyfitn from the file exchange, which can allow you to specify a specific model.

As easy for this very specific case is to use polyfit, on the transformed quadratic model:

Y = A + Bu + C u^2

where you define u as x^2. Get that from:

p=polyfit(x.^2,y,2);