dorm2l.f (3) Linux Manual Page

dorm2l.f –

Synopsis

Functions/Subroutines

subroutine dorm2l (SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, INFO)
DORM2L multiplies a general matrix by the orthogonal matrix from a QL factorization determined by sgeqlf (unblocked algorithm).

Function/Subroutine Documentation

subroutine dorm2l (characterSIDE, characterTRANS, integerM, integerN, integerK, double precision, dimension( lda, * )A, integerLDA, double precision, dimension( * )TAU, double precision, dimension( ldc, * )C, integerLDC, double precision, dimension( * )WORK, integerINFO)

DORM2L multiplies a general matrix by the orthogonal matrix from a QL factorization determined by sgeqlf (unblocked algorithm).

Purpose:

 DORM2L overwrites the general real m by n matrix C with

 Q * C if SIDE = ‘L’ and TRANS = ‘N’, or

 Q**T * C if SIDE = ‘L’ and TRANS = ‘T’, or

 C * Q if SIDE = ‘R’ and TRANS = ‘N’, or

 C * Q**T if SIDE = ‘R’ and TRANS = ‘T’,

 where Q is a real orthogonal matrix defined as the product of k

 elementary reflectors

 Q = H(k) . . . H(2) H(1)

 as returned by DGEQLF. Q is of order m if SIDE = ‘L’ and of order n

 if SIDE = ‘R’.

 

Parameters:

SIDE

 SIDE is CHARACTER*1

 = ‘L’: apply Q or Q**T from the Left

 = ‘R’: apply Q or Q**T from the Right

TRANS

 TRANS is CHARACTER*1

 = ‘N’: apply Q (No transpose)

 = ‘T’: apply Q**T (Transpose)

M

 M is INTEGER

 The number of rows of the matrix C. M >= 0.

N

 N is INTEGER

 The number of columns of the matrix C. N >= 0.

K

 K is INTEGER

 The number of elementary reflectors whose product defines

 the matrix Q.

 If SIDE = ‘L’, M >= K >= 0;

 if SIDE = ‘R’, N >= K >= 0.

A

 A is DOUBLE PRECISION array, dimension (LDA,K)

 The i-th column must contain the vector which defines the

 elementary reflector H(i), for i = 1,2,…,k, as returned by

 DGEQLF in the last k columns of its array argument A.

 A is modified by the routine but restored on exit.

LDA

 LDA is INTEGER

 The leading dimension of the array A.

 If SIDE = ‘L’, LDA >= max(1,M);

 if SIDE = ‘R’, LDA >= max(1,N).

TAU

 TAU is DOUBLE PRECISION array, dimension (K)

 TAU(i) must contain the scalar factor of the elementary

 reflector H(i), as returned by DGEQLF.

C

 C is DOUBLE PRECISION array, dimension (LDC,N)

 On entry, the m by n matrix C.

 On exit, C is overwritten by Q*C or Q**T*C or C*Q**T or C*Q.

LDC

 LDC is INTEGER

 The leading dimension of the array C. LDC >= max(1,M).

WORK

 WORK is DOUBLE PRECISION array, dimension

 (N) if SIDE = ‘L’,

 (M) if SIDE = ‘R’

INFO

 INFO is INTEGER

 = 0: successful exit

 < 0: if INFO = -i, the i-th argument had an illegal value

 

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

September 2012

Definition at line 159 of file dorm2l.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.