I would like to know the function of spy function in Octave. I have seen some
examples and I see that it is used to display in some form of dot matrix.
The documentation in Mathwords does not help much.
in octave. Spy is used to visualize the structure of sparse matrices,
or bolean matrices, or any matrix that is expected to have many zeros.
You get a plot with the shape of the matrix and a blue dot for each
non-zero entry. That's it!