I can see that Stochastic Gradient Descent has already been implemented. But linear regression works using simple gradient descent. What are the challenges to implementing SGD for Linear Regression.
SGD implementation: https://github.com/AtheMathmo/rusty-machine/blob/master/src/learning/optim/grad_desc.rs#L159
https://github.com/AtheMathmo/rusty-machine/blob/master/src/learning/lin_reg.rs#L157