Intel® oneMKL PARDISO Parameters in Tabular Form

Developer Reference for Intel® oneAPI Math Kernel Library for C

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ID 766684

Date 4/28/2026

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Intel® oneMKL PARDISO Parameters in Tabular Form

The following table lists all parameters of Intel® oneAPI Math Kernel Library (oneMKL) PARDISO and gives their brief descriptions.

Parameter	Type	Description	Values
`pt` in/out	`void *`	Solver internal data address pointer	0 Must be initialized with zeros and never be modified later
`maxfct` in	`MKL_INT *`	Maximal number of factors in memory	`\(>0\)` Generally used value is 1
`mnum` in	`MKL_INT *`	The number of matrix (from 1 to `maxfct` ) to solve	[1: `maxfct` ] Generally used value is 1
`mtype` in	`MKL_INT *`	Matrix type	1 - Real and structurally symmetric 2 - Real and symmetric positive definite -2 - Real and symmetric indefinite 3 - Complex and structurally symmetric 4 - Complex and Hermitian positive definite -4 - Complex and Hermitian indefinite 6 - Complex and symmetric matrix 11 - Real and nonsymmetric matrix 13 - Complex and nonsymmetric matrix
`phase` in	`MKL_INT *`	Controls the execution of the solver For iparm[35] > 0, phases 331, 332, and 333 perform a different decomposition. See the `phase` parameter of pardiso for details.	11 - Analysis 12 - Analysis, numerical factorization 13 - Analysis, numerical factorization, solve 22 - Numerical factorization 23 - Numerical factorization, solve 33 - Solve, iterative refinement 331 - `phase` =33, but only forward substitution 332 - `phase` =33, but only diagonal substitution 333 - `phase` =33, but only backward substitution 0 - Release internal memory for L and U of the matrix number `mnum` -1 - Release all internal memory for all matrices
`n` in	`MKL_INT *`	Number of equations in the sparse linear system `A` * `X` = `B`	`\(>0\)`
`a` in	`void *`	Contains the non-zero elements of the coefficient matrix `A`	* The size of `a` is the same as that of `ja` , and the coefficient matrix can be either real or complex. The matrix must be stored in the 3-array variation of compressed sparse row (CSR3) format with increasing values of `ja` for each row
`ia[n]` in	`MKL_INT *`	`rowIndex` array in CSR3 format	`\(\ge 0\)` `ia[i]` gives the index of the element in array `a` that contains the first non-zero element from row `i` of `A` . The last element `ia[n]` (for zero-based indexing) or `ia[n+1]` (for one-based indexing) is taken to be equal to the number of non-zero elements in `A` , plus one . Note: iparm[34] indicates whether row/column indexing starts from 1 or 0.
`ja` in	`MKL_INT *`	`columns` array in CSR3 format	`\(\ge 0\)` The column indices for each row of `A` must be sorted in increasing order. For structurally symmetric matrices zero diagonal elements must be stored in `a` and `ja` . Zero diagonal elements should be stored for symmetric matrices, although they are not required. For symmetric matrices, the solver needs only the upper triangular part of the system. Note: iparm[34] indicates whether row/column indexing starts from 1 or 0.
`perm[n]` in/out	`MKL_INT *`	Holds the permutation vector of size `n` , specifies elements used for computing a partial solution, or specifies differing values of the input matrices for low rank update	`\(\ge 0\)` You can apply your own fill-in reducing ordering ( iparm[4] = 1) or return the permutation from the solver ( iparm[4] = 2 ). Let `C = PAP^{T}` be the permuted matrix. Row (column) `i` of `C` is the `perm[i]` row (column) of `A` . The numbering of the array must describe a permutation. To specify elements for a partial solution, set iparm[4] = 0, iparm[30] > 0, and iparm[35] = 0. To specify elements for a Schur complement, set iparm[4] = 0, iparm[30] = 0, and iparm[35] > 0. To specify values that differ in `A` for low rank update (see Low Rank Update ), set iparm[38] = 1. The size of the array must be at least 2* `ndiff` + 1, where `ndiff` is the number of values of `A` that are different. The values of `perm` should be: `perm = {ndiff, row_index1, column_index1, row_index2, column_index2, ...., row_index_ndiff,column_index_ndiff}` where `row_index_m` and `column_index_m` are the row and column indices of the `m` -th differing non-zero value in matrix `A` . The row and column index pairs can be in any order, but must use zero-based indexing regardless of the value of iparm[34]. NOTE: Unless you have specified low rank update, iparm[34] indicates whether row/column indexing starts from 1 or 0.
`nrhs` in	`MKL_INT *`	Number of right-hand sides that need to be solved for	`\(\ge 0\)` Generally used value is 1 To obtain better Intel® oneMKL PARDISO performance, during the numerical factorization phase you can provide the maximum number of right-hand sides, which can be used further during the solving phase.
`iparm[64]` in/out	`MKL_INT *`	This array is used to pass various parameters to Intel® oneMKL PARDISO and to return some useful information after execution of the solver (see pardiso iparm Parameter for more details)	* If iparm[0] `=0` , PARDISO fills iparm[1] through iparm[63] with default values and uses them.
`msglvl` in	`MKL_INT *`	Message level information	0 - Intel® oneMKL PARDISO generates no output 1 - Intel® oneMKL PARDISO prints statistical information
`b[nnrhs]` in/out*	`void *`	Right-hand side vectors	* On entry, contains the right-hand side vector/matrix `B` , which is placed contiguously in memory. The `b[i+k*n]` element must hold the `i` -th component of `k` -th right-hand side vector. Note that `b` is only accessed in the solution phase. On output, the array is replaced with the solution if iparm[5] =1.
`x[nnrhs]` out*	`void *`	Solution vectors	* On output, if iparm[5] =0, contains solution vector/matrix `X` which is placed contiguously in memory. The `x[i+k*n]` element must hold the `i` -th component of `k` -th solution vector. Note that `x` is only accessed in the solution phase.
`error` out	`MKL_INT *`	Error indicator	0 - No error -1 - Input inconsistent -2 - Not enough memory -3 - Reordering problem -4 - Zero pivot, numerical factorization or iterative refinement problem -5 - Unclassified (internal) error -6 - Reordering failed (matrix types 11 and 13 only) -7 - Diagonal matrix is singular -8 - 32-bit integer overflow problem -9 - Not enough memory for OOC -10 - Problems with opening OOC temporary files -11 - Read/write problems with the OOC data file

[1]: See description of PARDISO_DATA_TYPE in PARDISO_DATA_TYPE .