MATLAB: Plotting sparsity pattern of a matrix

sparsity matrix spy()

Hi Guys,

I want to visualize the sparsity pattern of a sparse matrix using the function spy().All elements in this matrix is approximated to 4th digit (example : 0.0031,0.0000). The spy() function does not identify 0.0000 or -0.0000 s as absolute zeros. I mean the pattern seems to be dense. How can I overcome this issue? please help me.

Best Answer

spy(abs(yourMatrix)>=0.0001)

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MATLAB: How to make a permanent change to a matrix using sortrows

 P = sortrows(P,7) ;

Most of the time functions don't operate "externally", so SORTROWS doesn't alter your array P defined in the workspace. It creates a new sorted array that it outputs. You have to store this output back into P if you want P to be the sorted version. If you wanted to keep the original, you could store it into a new variable:

 P_sorted = sortrows(P,7) ;

MATLAB: Computing generalized Inverse of a square but sparse matrix

Hi,

The disadvantages of using ‘pinv’ to find inverse of sparse matrix are:

‘pinv’ requires costly SVD.
‘pinv’ does not work with sparse matrix.

Instead, you can use the function ‘pseudo-inverse’ for the same purpose. Refer the following link for documentation of ‘pseudo-inverse’ function.

Hope this helps!

Best Answer

Related Solutions

MATLAB: How to make a permanent change to a matrix using sortrows

MATLAB: Computing generalized Inverse of a square but sparse matrix

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