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Hi,

I sent a post a couple of weeks ago, but I would like to specify my problem.

I want to solve a linear system of type Ax = b, for a common matrix A ( nonsymmetric, not positive-definite...), and b, x vectors.

Pardiso perfectly works in most of cases, but for my set of input data (see attached), it doesn't work: the result I obtain is totally aberrant. This is weird since A is inversible and very well conditionned (4.9819).

Here are my iparms :

357 iparm[0] = 1; /* No solver default */

358 iparm[1] = 2; /* Fill-in reordering from METIS */

359 iparm[2] = 8;

360 iparm[3] = 0; /* CGS */

361 iparm[4] = 0; /* No user fill-in reducing permutation */

362 iparm[5] = 0; /* Write solution into x */

363 iparm[6] = 0; /* Not in use */

364 iparm[7] = 0; /* Max numbers of iterative refinement steps */

365 iparm[8] = 0; /* Not in use */

366 iparm[9] = 13; /* Perturb the pivot elements with 1E-13 */

367 iparm[10] = 1; /* Use nonsymmetric permutation and scaling MPS */

368 iparm[11] = 0; /* Not in use */

369 iparm[12] = 0; /* Not in use */

370 iparm[13] = 0; /* Output: Number of perturbed pivots */

371 iparm[14] = 0; /* Not in use */

372 iparm[15] = 0; /* Not in use */

373 iparm[16] = 0; /* Not in use */

374 iparm[17] = -1; /* Output: Number of nonzeros in the factor LU */

375 iparm[18] = -1; /* Output: Mflops for LU factorization */

376 iparm[19] = 0; /* Output: Numbers of CG Iterations */

377 iparm[27] = 1; /* check the data structure */

378 iparm[31] = 1; /* iterative solver*/

380 maxfct = 1; /* Maximum number of numerical factorizations. */

381 mnum = 1; /* Which factorization to use. */

The Package ID of mkl is : l_mkl_p_10.0.011

Thanks for any help you can give me

Antoine

ps. A is stored in CSR format. Its file is composed of 4 lines : the size of datas (row column val), the ranks of the first element of the row, the columns, and the values. Tell me if you want another format.

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To have Pardiso check your matrix, set iparm[26]=1 (not iparm[27]=1 as you did).

The array ia must have one more entry: the last entry should be set as m_row[m_dim]=m_nnz+1; this is the CSR storage convention. You left this item undefined but, because of the preceding error, Pardiso did no checking of the matrix.
You have loops such as
* += 1;
** -= 1;
***indices** of arrays b and x that may be zero- or one-based, not their **values**.

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mecej4 wrote:You are right, this really make no sens. Actually, I haven't done that in my real program. I needed to change the program a little and I added that, I don't know why.These make no sense. It is the indices of arrays b and x that may be zero- or one-based, not their values.

mecej4 wrote:This is done by m_row.push_back(m_val.size()+1);the last entry should be set as m_row[m_dim]=m_nnz+1

mecej4 wrote:I have just tried this... My matrix seems to be correctly input.To have Pardiso check your matrix, set iparm[26]=1

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Had you chosen the solver defaults for your matrix type, you would have had a working program quickly, which you could then tweak by modifying the iparm[] values to your satisfaction.

However, you chose to set iparm[0] to a non-zero value at the outset, which then shifted the responsibility to you for setting all 64 values correctly, taking into account the documentation's 1-based indexing and your C++ program's 0-based indexing.

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