Why do we drop the summation term in the derivative of the regularized cost function


It’s mentioned in the video but not really explained, can someone explain to me why that happens

Hi @rmwkwok Raymond,

I think you had replied to this doubt recently. Probably you can direct to the same post.


It’s because in a partial derivative, each weight is considered separately, and all the other weights are considered as constants.

Since the partial derivative of a constant is zero, all the other “non-j” terms become zeros, so they evaporate from the equation for each w_j.