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Why the sparse pattern of a sparse matrix changed

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Rylan
Rylan on 11 Apr 2021
Commented: Rylan on 11 Apr 2021
I'm building a sparse matrix through the mex function. Both the Ir and Jc properties are appointed in the mex function A. Later, this sparse matrix is returned to matlab, and is further transferred to another mex function B together with other parameters to assemble a large matrix.
For one test case, part of the Jc property of the created sparse matrix in the mex function A is as follows:
368
392
416
440
464
488
512
But when this sparse matrix is further transferred to mex function B, this part is altered and is as follows:
368
392
416
440
463
487
511
Actually, after this sparse matrix is established, I did no alternation about it. I want to know what may case this.
  4 Comments
Rylan
Rylan on 11 Apr 2021
(9,22) -0.0000
(10,22) 0
(11,22) 0.0000
(12,22) -0.0000
(13,22) -0.2500
(14,22) 0.5000
It seems problem was caused by (10,22), and use of spok indicate that "0 jumbled row indices, 3 explicit zeros". To remove this problem, may be a vary small number, for example, 1e-16, should be added to all the data member.
Thanks for your suggestion!

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Accepted Answer

Bruno Luong
Bruno Luong on 11 Apr 2021
The mex probably creates a non-valid sparse matrix, use spok to check validity

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