MATLAB: Linear fit with fitlm or regress

Question

Hi

I have a data set of three variables. I want to use the equation y = a + b*temp + c*temp* sigma. When i write this like y~temp+(sigma*temp) in fitlm, I get 4 terms, Intercept, temp, sigma and temp:sigma.

My question is if sigma is the slope c and temp:sigma is temp*sigma for the c? I think this is correct, but I have not been able to figure out how the equation would look like based on the input arguments. The displayed "Linear regression model" is y ~1 + t*sigma

Thanks a lot!

Answer 1

Your three variables are y, temp, and sigma? If I understand the model you want to fit, you might get a cleaner picture if you form a new variable:

prod = temp.*sigma;

and then use

y~temp+prod