Developer Reference for Intel® oneAPI Math Kernel Library for C

ID 766684
Date 3/31/2023
Public

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Extended Eigensolver Input Parameters

The input parameters for Extended Eigensolver routines are contained in an MKL_INT array named fpm. To call the Extended Eigensolver interfaces, this array should be initialized using the routine feastinit.

Parameter

Default

Description

fpm[0]

0

Specifies whether Extended Eigensolver routines print runtime status.

fpm[0]=0

Extended Eigensolver routines do not generate runtime messages at all.

fpm[0]=1

Extended Eigensolver routines print runtime status to the screen.

fpm[1]

8

The number of contour points Ne = 8 (see the description of FEAST algorithm). Must be one of {3,4,5,6,8,10,12,16,20,24,32,40,48}.

fpm[2]

12

Error trace double precision stopping criteria ε (ε = 10-fpm[2]) .

fpm[3]

20

Maximum number of Extended Eigensolver refinement loops allowed. If no convergence is reached within fpm[3] refinement loops, Extended Eigensolver routines return info=2.

fpm[4]

0

User initial subspace. If fpm[4]=0 then Extended Eigensolver routines generate initial subspace, if fpm[4]=1 the user supplied initial subspace is used.

fpm[5]

0

Extended Eigensolver stopping test.

fpm[5]=0

Extended Eigensolvers are stopped if this residual stopping test is satisfied:

  • generalized eigenvalue problem:

  • standard eigenvalue problem:

where mode is the total number of eigenvalues found in the search interval and ε = 10-fpm[6] for real and complex or ε = 10-fpm[2] for double precision and double complex.

fpm[5]=1

Extended Eigensolvers are stopped if this trace stopping test is satisfied:

,

where tracej denotes the sum of all eigenvalues found in the search interval [emin, emax] at the j-th Extended Eigensolver iteration:

.

fpm[6]

5

Error trace single precision stopping criteria (10-fpm[6]) .

fpm[13]

0

fpm[13]=0

Standard use for Extended Eigensolver routines.

fpm[13]=1

Non-standard use for Extended Eigensolver routines: return the computed eigenvectors subspace after one single contour integration.

fpm[26]

0

Specifies whether Extended Eigensolver routines check input matrices (applies to CSR format only).

fpm[26]=0

Extended Eigensolver routines do not check input matrices.

fpm[26]=1

Extended Eigensolver routines check input matrices.

fpm[27]

0

Check if matrix B is positive definite. Set fpm[27] = 1 to check if B is positive definite.

fpm[29] to fpm[62]

-

Reserved for future use.

fpm[63]

0

Use the Intel® oneAPI Math Kernel Library PARDISO solver with the user-defined PARDISOiparm array settings.

NOTE:

This option can only be used by Extended Eigensolver Predefined Interfaces for Sparse Matrices.

fpm[63]=0

Extended Eigensolver routines use the Intel® oneAPI Math Kernel Library PARDISO defaultiparm settings defined by calling the pardisoinit subroutine.

fpm[63]=1

The values from fpm[64] to fpm[127] correspond to iparm[0] to iparm[63] respectively according to the formula fpm[64 + i]= iparm[i] for i = 0, 1, ..., 63.