SORMRQ (3) Linux Manual Page

sormrq.f –

Synopsis

Functions/Subroutines

subroutine sormrq (SIDE, TRANS, M, N, K, A, LDA, TAU, C, LDC, WORK, LWORK, INFO)
SORMRQ

Function/Subroutine Documentation

subroutine sormrq (characterSIDE, characterTRANS, integerM, integerN, integerK, real, dimension( lda, * )A, integerLDA, real, dimension( * )TAU, real, dimension( ldc, * )C, integerLDC, real, dimension( * )WORK, integerLWORK, integerINFO)

SORMRQ

Purpose:

 SORMRQ overwrites the general real M-by-N matrix C with

 SIDE = ‘L’ SIDE = ‘R’

 TRANS = ‘N’: Q * C C * Q

 TRANS = ‘T’: Q**T * C C * Q**T

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

 elementary reflectors

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

 as returned by SGERQF. 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’: No transpose, apply Q;

 = ‘T’: Transpose, apply Q**T.

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 REAL array, dimension

 (LDA,M) if SIDE = ‘L’,

 (LDA,N) if SIDE = ‘R’

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

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

 SGERQF in the last k rows of its array argument A.

LDA

 LDA is INTEGER

 The leading dimension of the array A. LDA >= max(1,K).

TAU

 TAU is REAL array, dimension (K)

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

 reflector H(i), as returned by SGERQF.

C

 C is REAL 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 REAL array, dimension (MAX(1,LWORK))

 On exit, if INFO = 0, WORK(1) returns the optimal LWORK.

LWORK

 LWORK is INTEGER

 The dimension of the array WORK.

 If SIDE = ‘L’, LWORK >= max(1,N);

 if SIDE = ‘R’, LWORK >= max(1,M).

 For optimum performance LWORK >= N*NB if SIDE = ‘L’, and

 LWORK >= M*NB if SIDE = ‘R’, where NB is the optimal

 blocksize.

 If LWORK = -1, then a workspace query is assumed; the routine

 only calculates the optimal size of the WORK array, returns

 this value as the first entry of the WORK array, and no error

 message related to LWORK is issued by XERBLA.

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:

November 2011

Definition at line 170 of file sormrq.f.

Author

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