Stepwise regression output formula

Hi,

I tried to find a regression formula using:

mdl = LinearModel.stepwise(X,y);

where X is a mx3-matrix.

The output gives me:

Linear regression model: y ~ 1 + x1*x2 + x2*x3

With the estimated coefficients and this formula I tried to get the same results when using:

feval(mdl,Test_vals)

I also tried to convert the formula using Wilkinsons notation...

x1*x2 = x1 + x2 + x1*x2

but I still get different results :(

Any ideas?

Thanks, Moritz