optimization variables X will not be copied at the beginning but themselves updated;
the reference to the variable is held throughout the entire optimization, i.e. all modifications are guaranteed to be on the same data container.
The second part is important for a new feature of scarlet (namely to resize the sources without having to restart the optimization by exception). It allows user code to change the shape of X internally during a call to prox_f.
This PR contains two related changes
Xwill not be copied at the beginning but themselves updated;The second part is important for a new feature of scarlet (namely to resize the sources without having to restart the optimization by exception). It allows user code to change the shape of
Xinternally during a call toprox_f.