Why the sparse pattern of a sparse matrix changed

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Rylan
Rylan 2021 年 4 月 11 日
コメント済み: James Tursa 2024 年 1 月 28 日
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 件のコメント
Bruno Luong
Bruno Luong 2021 年 4 月 11 日
You MUST NOT store 0 elements internally. Use spok I indicate bellow to check if your mex-build result is valid.
Rylan
Rylan 2021 年 4 月 11 日
(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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Bruno Luong
Bruno Luong 2021 年 4 月 11 日
The mex probably creates a non-valid sparse matrix, use spok to check validity
  1 件のコメント
James Tursa
James Tursa 2024 年 1 月 28 日
Note that Tim Davis's spok function has been removed from the FEX. You can use my replacement function sarek instead:

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