Visible to Intel only — GUID: GUID-AB6FF030-CD8B-4589-B203-BFE3666B1E5E
Visible to Intel only — GUID: GUID-AB6FF030-CD8B-4589-B203-BFE3666B1E5E
p?lanhs
Returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element, of an upper Hessenberg matrix.
Syntax
val = pslanhs(norm, n, a, ia, ja, desca, work)
val = pdlanhs(norm, n, a, ia, ja, desca, work)
val = pclanhs(norm, n, a, ia, ja, desca, work)
val = pzlanhs(norm, n, a, ia, ja, desca, work)
Description
The p?lanhsroutine returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of an upper Hessenberg distributed matrix sub(A) = A(ia:ia+m-1, ja:ja+n-1).
Input Parameters
- norm
-
CHARACTER*1. Specifies the value to be returned by the routine:
= 'M' or 'm': val = max(abs(Aij)), largest absolute value of the matrix A.
= '1' or 'O' or 'o': val = norm1(A), 1-norm of the matrix A (maximum column sum),
= 'I' or 'i': val = normI(A), infinity norm of the matrix A (maximum row sum),
= 'F', 'f', 'E' or 'e': val = normF(A), Frobenius norm of the matrix A (square root of sum of squares).
- n
-
(global) INTEGER.
The number of columns in the distributed matrix sub(A). When n = 0, p?lanhs is set to zero. n≥ 0. - a
-
(local).
REAL for pslanhs
DOUBLE PRECISION for pdlanhs
COMPLEX for pclanhs
COMPLEX*16 for pzlanhs.
Pointer into the local memory to an array of size (lld_a, LOCc(ja+n-1)) containing the local pieces of the distributed matrix sub(A).
- ia, ja
-
(global) INTEGER.
The row and column indices in the global matrix A indicating the first row and the first column of the matrix sub(A), respectively.
- desca
-
(global and local) INTEGER array of size dlen_. The array descriptor for the distributed matrix A.
- work
-
(local).
REAL for pslanhs
DOUBLE PRECISION for pdlanhs
COMPLEX for pclanhs
COMPLEX*16 for pzlanh.
Array of size lwork.
lwork ≥ 0 if norm = 'M' or 'm' (not referenced),
nq0 if norm = '1', 'O' or 'o',
mp0 if norm = 'I' or 'i',
0 if norm = 'F', 'f', 'E' or 'e' (not referenced),
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 ),
mp0 = numroc( m+iroffa, mb_a, myrow, iarow, nprow ),
nq0 = numroc( n+icoffa, nb_a, mycol, iacol, npcol ),
indxg2p and numroc are ScaLAPACK tool routines; myrow, imycol, nprow, and npcol can be determined by calling the subroutine blacs_gridinfo.
Output Parameters
- val
-
The value returned by the function.