Developer Reference for Intel® oneAPI Math Kernel Library for C
p?ungql
Generates the unitary matrix Q of the QL factorization formed by p?geqlf .
Syntax
voidpcungql ( constMKL_INT*m , constMKL_INT*n , constMKL_INT*k , MKL_Complex8*a , constMKL_INT*ia , constMKL_INT*ja , constMKL_INT*desca , constMKL_Complex8*tau , MKL_Complex8*work , constMKL_INT*lwork , MKL_INT*info );
voidpzungql ( constMKL_INT*m , constMKL_INT*n , constMKL_INT*k , MKL_Complex16*a , constMKL_INT*ia , constMKL_INT*ja , constMKL_INT*desca , constMKL_Complex16*tau , MKL_Complex16*work , constMKL_INT*lwork , MKL_INT*info );
Include Files
mkl_scalapack.h
Description
pcungql pzungql This routine function generates the whole or part of m -by- n complex distributed matrix Q denoting A ( ia : ia + m -1, ja : ja + n -1) with orthonormal rows, which is defined as the first n columns of a product of k elementary reflectors of order m
Q = ( H ( k )) :code:`H` …*( H (2)) :code:`H` *( H (1)) :code:`H` as returned by p?geqlf (Computes the QL factorization of a general matrix.) .
Input Parameters
m
(global) The number of rows in the matrix sub( Q ) (m≥0) .
n
(global) The number of columns in the matrix sub( Q ) (m≥n≥0) .
k
(global) The number of elementary reflectors whose product defines the matrix Q(n≥k≥0) .
- a
-
(local) COMPLEX for pcungql DOUBLE COMPLEX for pzungql
ia , ja
(global) The row and column indices in the global matrix A indicating the first row and the first column of the submatrix A ( ia : ia + m -1, ja : ja + n -1), respectively.
desca
(global and local) array of size dlen_ . The array descriptor for the distributed matrix A .
- tau
-
(local) COMPLEX for pcungql DOUBLE COMPLEX for pzungql Array of size LOCr ( ia + n -1).
Contains the scalar factors tau [ j ] of elementary reflectors H ( j +1), 0 ≤ j < LOCr(ia+n-1) . tau is tied to the distributed matrix A .
- work
-
(local) COMPLEX for pcungql DOUBLE COMPLEX for pzungql Workspace array of size of lwork .
lwork
(local or global) size of work , must be at least lwork≥nb_a*(nqa0 + mpa0 + nb_a) , where
iroffa = mod(ia-1, mb_a) , icoffa = mod(ja-1, nb_a) , iarow = indxg2p(ia, mb_a, MYROW, rsrc_a, NPROW) , iacol = indxg2p(ja, nb_a, MYCOL, csrc_a, NPCOL) , mpa0 = numroc(m+iroffa, mb_a, MYROW, iarow, NPROW) , nqa 0 = numroc ( n + icoffa , nb_a , MYCOL , iacol , NPCOL )
indxg2p and numroc are ScaLAPACK tool functions; MYROW , MYCOL , NPROW and NPCOL can be determined by calling the function blacs_gridinfo .
If lwork = -1 , then lwork is global input and a workspace query is assumed; the function only calculates the minimum and optimal size for all work arrays. Each of these values is returned in the first entry of the corresponding work array, and no error message is issued by pxerbla .
Output Parameters
- a
-
Contains the local pieces of the m -by- n distributed matrix Q to be factored.
work(1)[0]
On exit, work(1)[0] contains the minimum value of lwork required for optimum performance.
info
(global)
= 0 : the execution is successful.
< 0 : if the i -th argument is an array and the j- th entry , indexed j - 1, had an illegal value, then info = -( i *100+ j ); if the i- th argument is a scalar and had an illegal value, then info = -i .