reading ldoor matrix and incomplete factorization?

Question

I tried to read in the ldoor matrix and attempted the LLT factorization but it gives me: "parseLdoor[55178:5595352] Factored does not hold a completed matrix factorization. (lldb)"

Because the ldoor matrix is large I have not been able to discover the issue. I am unsure if the matrix data was converted correctly via the SparseConvertFromCoordinate function. Otoh, I was able to use the same code to get the correct answers for the simple 4x4 example used in the Sparse Solver documentation. Any help would be appreciated.

Here is my code ... without the ldoor matrix

254

Posted by

williamfromalfred

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Answer 1

I re-tested on the 4x4 example given in Apple documentation on Creating a Sparse Matrix from Coordinate Format Arrays. Adjusted all the coordinates up by 1 and ran with the code with the - 1 to reduce the coordinate rows and columns coordinates just to be sure. Everything works (answers are correct). So, I just have to remember when downloading to check the coordinates to see where they start, and adjust if need be.

Posted by

williamfromalfred

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Answer 2

I am more than dumb ... but may I be excused for being such an amateur? Not! Haha.

So, I thought I could use the Ldoor matrix directly after stripping off the headers. That part I got right. But I failed to realize in order to use the SparseConvertFromCoordinate I was required to adjust the coordinate format row and column number from 1, 1 to 0, 0 , and, of course, for all subsequent coordinate format rows and columns.

I updated the original code with this part of code which reduces coordinate numbers by 1. And everything ran! Well, at least I got some answers and exit code 0.

// assign forced unwrapping for casting to appropriate arrays

for index in 0...rowcountm1 {

rows32[index] = Int32(rows![index] - 1 )

cols32[index] = Int32(cols![index] - 1 )

datsdouble[index] = Double(dats![index])

}

Posted by

williamfromalfred

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Answer 3

I re-tested on the 4x4 example given in Apple documentation on Creating a Sparse Matrix from Coordinate Format Arrays. Adjusted all the coordinates up by 1 and ran with the code with the - 1 to reduce the coordinate rows and columns coordinates just to be sure. Everything works (answers are correct). So, I just have to remember when downloading to check the coordinates to see where they start, and adjust if need be.

Posted by

williamfromalfred

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reading ldoor matrix and incomplete factorization?

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