NAME

dopgtr.f -

SYNOPSIS


Functions/Subroutines


subroutine dopgtr (UPLO, N, AP, TAU, Q, LDQ, WORK, INFO)
DOPGTR

Function/Subroutine Documentation

subroutine dopgtr (characterUPLO, integerN, double precision, dimension( * )AP, double precision, dimension( * )TAU, double precision, dimension( ldq, * )Q, integerLDQ, double precision, dimension( * )WORK, integerINFO)

DOPGTR

Purpose:

 DOPGTR generates a real orthogonal matrix Q which is defined as the
 product of n-1 elementary reflectors H(i) of order n, as returned by
 DSPTRD using packed storage:

 if UPLO = 'U', Q = H(n-1) . . . H(2) H(1),

 if UPLO = 'L', Q = H(1) H(2) . . . H(n-1).


 

Parameters:

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.


N

          N is INTEGER
          The order of the matrix Q. N >= 0.


AP

          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
          The vectors which define the elementary reflectors, as
          returned by DSPTRD.


TAU

          TAU is DOUBLE PRECISION array, dimension (N-1)
          TAU(i) must contain the scalar factor of the elementary
          reflector H(i), as returned by DSPTRD.


Q

          Q is DOUBLE PRECISION array, dimension (LDQ,N)
          The N-by-N orthogonal matrix Q.


LDQ

          LDQ is INTEGER
          The leading dimension of the array Q. LDQ >= max(1,N).


WORK

          WORK is DOUBLE PRECISION array, dimension (N-1)


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 115 of file dopgtr.f.

Author

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