Visible to Intel only — GUID: GUID-A1C86B84-4D0B-4ADE-B4FD-333255AE9413
Visible to Intel only — GUID: GUID-A1C86B84-4D0B-4ADE-B4FD-333255AE9413
p?lantr
Returns the value of the 1-norm, Frobenius norm, infinity-norm, or the largest absolute value of any element, of a triangular matrix.
Syntax
val = pslantr(norm, uplo, diag, m, n, a, ia, ja, desca, work)
val = pdlantr(norm, uplo, diag, m, n, a, ia, ja, desca, work)
val = pclantr(norm, uplo, diag, m, n, a, ia, ja, desca, work)
val = pzlantr(norm, uplo, diag, m, n, a, ia, ja, desca, work)
Description
The p?lantrroutine returns the value of the 1-norm, or the Frobenius norm, or the infinity norm, or the element of largest absolute value of a trapezoidal or triangular distributed matrix sub(A) = A(ia:ia+m-1, ja:ja+n-1).
Input Parameters
- norm
-
(global) CHARACTER. Specifies what value is returned by the routine:
= 'M' or 'm': val = max(abs(Aij)), largest absolute value of the matrix A, it s not a matrix norm.
= '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).
- uplo
-
(global) CHARACTER.
Specifies whether the upper or lower triangular part of the symmetric matrix sub(A) is to be referenced.
= 'U': Upper trapezoidal,
= 'L': Lower trapezoidal.
Note that sub(A) is triangular instead of trapezoidal if m = n.
- diag
-
(global) CHARACTER.
Specifies whether the distributed matrix sub(A) has unit diagonal.
= 'N': Non-unit diagonal.
= 'U': Unit diagonal.
- m
-
(global) INTEGER.
The number of rows in the distributed matrix sub(A). When m = 0, p?lantr is set to zero. m ≥ 0.
- n
-
(global) INTEGER.
The number of columns in the distributed matrix sub(A). When n = 0, p?lantr is set to zero. n ≥ 0.
- a
-
(local).
REAL for pslantr
DOUBLE PRECISION for pdlantr
COMPLEX for pclantr
COMPLEX*16 for pzlantr.
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 pslantr
DOUBLE PRECISION for pdlantr
COMPLEX for pclantr
COMPLEX*16 for pzlantr.
Array 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),
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 functions; myrow, mycol, nprow, and npcol can be determined by calling the subroutine blacs_gridinfo.
Output Parameters
- val
-
The value returned by the routine.