Intel® oneAPI Math Kernel Library Developer Reference - Fortran
Used by ?stedc. Computes the Z vector determining the rank-one modification of the diagonal matrix. Used when the original matrix is dense.
call slaeda( n, tlvls, curlvl, curpbm, prmptr, perm, givptr, givcol, givnum, q, qptr, z, ztemp, info )
call dlaeda( n, tlvls, curlvl, curpbm, prmptr, perm, givptr, givcol, givnum, q, qptr, z, ztemp, info )
The routine ?laeda computes the Z vector corresponding to the merge step in the curlvl-th step of the merge process with tlvls steps for the curpbm-th problem.
INTEGER. The dimension of the symmetric tridiagonal matrix (n≥ 0).
INTEGER. The total number of merging levels in the overall divide and conquer tree.
INTEGER. The current level in the overall merge routine, 0 ≤ curlvl ≤ tlvls .
INTEGER. The current problem in the current level in the overall merge routine (counting from upper left to lower right).
INTEGER. Arrays, dimension (n log2n ) each.
The array prmptr(*) contains a list of pointers which indicate where in perm a level's permutation is stored. prmptr(i+1) - prmptr(i) indicates the size of the permutation and also the size of the full, non-deflated problem.
The array perm(*) contains the permutations (from deflation and sorting) to be applied to each eigenblock.
The array givptr(*) contains a list of pointers which indicate where in givcol a level's Givens rotations are stored. givptr(i+1) - givptr(i) indicates the number of Givens rotations.
INTEGER. Array, dimension (2, n log2n ).
Each pair of numbers indicates a pair of columns to take place in a Givens rotation.
REAL for slaeda
DOUBLE PRECISION for dlaeda.
Array, dimension (2, n log2n).
Each number indicates the S value to be used in the corresponding Givens rotation.
REAL for slaeda
DOUBLE PRECISION for dlaeda.
Array, dimension ( n2).
Contains the square eigenblocks from previous levels, the starting positions for blocks are given by qptr.
INTEGER. Array, dimension (n+2). Contains a list of pointers which indicate where in q an eigenblock is stored. sqrt( qptr(i+1) - qptr(i)) indicates the size of the block.
REAL for slaeda
DOUBLE PRECISION for dlaeda.
Workspace array, dimension (n).
REAL for slaeda
DOUBLE PRECISION for dlaeda.
Array, dimension (n). Contains the updating vector (the last row of the first sub-eigenvector matrix and the first row of the second sub-eigenvector matrix).
INTEGER.
If info = 0, the execution is successful.
If info = -i, the i-th parameter had an illegal value.