Zygote - parametrize matrix such that gradient is only performed on selected coefficients

I was wondering if it was possible to parametrize matrices such that zygote’s gradient would only be performed on the selected coefficients of the matrix.

Some dummy code would look like:

theta = randn(2)
W = [theta[1] theta[2]; 0.0 theta[1]]
b = randn(100)
x = randn(2, 100)

gs = gradient(w -> sum(w*x+b), W)

However the gradient would only be performed on the values of theta, keeping W[2, 1] set to 0.0 for the entire gradient descent. Also this would imply that the gradients for theta[1] and theta[2] be equal at all times.
Am I completely going at this wrong way? or is it just not possible in julia?

You have the right idea, but you need to take the gradient w.r.t. theta instead of W, just wrap the function that accepts W in a function that accepts theta instead.