Zero out rows data
This MR adds the structure that is necessary to set to zero the entries of the data that are not covered by a linear operator. This is motivated by #30 (closed) .
The commits belonging to this MR add the self.data_mask property to the AbstractLinearOperator class and an implementation of the property to all the derived classes. Additionally, it implements the talon.utils.mask_data
function that does exactly the job that it is supposed to do given a data vector and a linear operator.
The corresponding tests are implemented.
Edited by FRIGO Matteo