dopmtr.f (3) Linux Manual Page

dopmtr.f –

Synopsis

Functions/Subroutines

subroutine dopmtr (SIDE, UPLO, TRANS, M, N, AP, TAU, C, LDC, WORK, INFO)
DOPMTR

Function/Subroutine Documentation

subroutine dopmtr (characterSIDE, characterUPLO, characterTRANS, integerM, integerN, double precision, dimension( * )AP, double precision, dimension( * )TAU, double precision, dimension( ldc, * )C, integerLDC, double precision, dimension( * )WORK, integerINFO)

DOPMTR

Purpose:

 DOPMTR 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 of order nq, with nq = m if

 SIDE = ‘L’ and nq = n if SIDE = ‘R’. Q is defined as the product of

 nq-1 elementary reflectors, as returned by DSPTRD using packed

 storage:

 if UPLO = ‘U’, Q = H(nq-1) . . . H(2) H(1);

 if UPLO = ‘L’, Q = H(1) H(2) . . . H(nq-1).

 

Parameters:

SIDE

 SIDE is CHARACTER*1

 = ‘L’: apply Q or Q**T from the Left;

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

UPLO

 UPLO is CHARACTER*1

 = ‘U’: Upper triangular packed storage used in previous

 call to DSPTRD;

 = ‘L’: Lower triangular packed storage used in previous

 call to DSPTRD.

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.

AP

 AP is DOUBLE PRECISION array, dimension

 (M*(M+1)/2) if SIDE = ‘L’

 (N*(N+1)/2) if SIDE = ‘R’

 The vectors which define the elementary reflectors, as

 returned by DSPTRD. AP is modified by the routine but

 restored on exit.

TAU

 TAU is DOUBLE PRECISION array, dimension (M-1) if SIDE = ‘L’

 or (N-1) if SIDE = ‘R’

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

 reflector H(i), as returned by DSPTRD.

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:

November 2011

Definition at line 150 of file dopmtr.f.

Author

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