Hello Theano Group - My name is Tomojit Ghosh and I'm doing my PhD in Machine Learning here in Colorado State University,USA. I'm looking to use Theano's Symbolic Differentiation.
I've a question on calculating the partial derivatives of a l1-pernalty function. The absolute value function is not differentiable at the point 0. The common approach is to take the sign of the individual elements to compute the partial derivative, in other words: partial of w_i=-1 if w_i<0, partial of w_i=+1 if w_i>0, partial of w_i=0 if w_i=0. Although I'm quite aware of the fact that when w_i=0, it's not differentiable. I'm not sure how symbolic differentiotion is computing the gradient of w_i when the value is zero. It'll be really helpful if you can shed some light onto this.Thank you very much for your time. Regards, Tomojit -- --- You received this message because you are subscribed to the Google Groups "theano-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
