sopgtr (l) - Linux Manuals

sopgtr: 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 SSPTRD using packed storage

Command to display sopgtr manual in Linux: $ man l sopgtr

NAME

SOPGTR - 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 SSPTRD using packed storage

SYNOPSIS

SUBROUTINE SOPGTR(: UPLO, N, AP, TAU, Q, LDQ, WORK, INFO )
: CHARACTER UPLO
: INTEGER INFO, LDQ, N
: REAL AP( * ), Q( LDQ, * ), TAU( * ), WORK( * )

PURPOSE

SOPGTR 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 SSPTRD using packed storage: if UPLO = aqUaq, Q = H(n-1) . . . H(2) H(1),
if UPLO = aqLaq, Q = H(1) H(2) . . . H(n-1).

ARGUMENTS

UPLO (input) CHARACTER*1: = aqUaq: Upper triangular packed storage used in previous call to SSPTRD; = aqLaq: Lower triangular packed storage used in previous call to SSPTRD.
N (input) INTEGER: The order of the matrix Q. N >= 0.
AP (input) REAL array, dimension (N*(N+1)/2): The vectors which define the elementary reflectors, as returned by SSPTRD.
TAU (input) REAL array, dimension (N-1): TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by SSPTRD.
Q (output) REAL array, dimension (LDQ,N): The N-by-N orthogonal matrix Q.
LDQ (input) INTEGER: The leading dimension of the array Q. LDQ >= max(1,N).
WORK (workspace) REAL array, dimension (N-1)
INFO (output) INTEGER: = 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value