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cgemqrt-f(3)

cgemqrt.f –

Synopsis

Functions/Subroutines

subroutine cgemqrt (SIDE, TRANS, M, N, K, NB, V, LDV, T, LDT, C, LDC, WORK, INFO)
CGEMQRT

Function/Subroutine Documentation

subroutine cgemqrt (characterSIDE, characterTRANS, integerM, integerN, integerK, integerNB, complex, dimension( ldv, * )V, integerLDV, complex, dimension( ldt, * )T, integerLDT, complex, dimension( ldc, * )C, integerLDC, complex, dimension( * )WORK, integerINFO)

CGEMQRT

Purpose:

 CGEMQRT overwrites the general complex M-by-N matrix C with
 SIDE = 'L' SIDE = 'R'
 TRANS = 'N': Q C C Q
 TRANS = 'C': Q**H C C Q**H
 where Q is a complex orthogonal matrix defined as the product of K
 elementary reflectors:
 Q = H(1) H(2) . . . H(K) = I - V T V**H
 generated using the compact WY representation as returned by CGEQRT. 
 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**H from the Left;
 = 'R': apply Q or Q**H from the Right.

TRANS

 TRANS is CHARACTER*1
 = 'N': No transpose, apply Q;
 = 'C': Transpose, apply Q**H.

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.

NB

 NB is INTEGER
 The block size used for the storage of T. K >= NB >= 1.
 This must be the same value of NB used to generate T
 in CGEQRT.

V

 V is COMPLEX array, dimension (LDV,K)
 The i-th column must contain the vector which defines the
 elementary reflector H(i), for i = 1,2,...,k, as returned by
 CGEQRT in the first K columns of its array argument A.

LDV

 LDV is INTEGER
 The leading dimension of the array V.
 If SIDE = 'L', LDA >= max(1,M);
 if SIDE = 'R', LDA >= max(1,N).

T

 T is COMPLEX array, dimension (LDT,K)
 The upper triangular factors of the block reflectors
 as returned by CGEQRT, stored as a NB-by-N matrix.

LDT

 LDT is INTEGER
 The leading dimension of the array T. LDT >= NB.

C

 C is COMPLEX array, dimension (LDC,N)
 On entry, the M-by-N matrix C.
 On exit, C is overwritten by Q C, Q**H C, C Q**H or C Q.

LDC

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

WORK

 WORK is COMPLEX array. The dimension of WORK is
 N*NB if SIDE = 'L', or M*NB 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:

November 2011

Definition at line 168 of file cgemqrt.f.

Author

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