cupgtr (l) - Linux Man Pages

cupgtr: generates a complex unitary matrix Q which is defined as the product of n-1 elementary reflectors H(i) of order n, as returned by CHPTRD using packed storage

NAME

CUPGTR - generates a complex unitary matrix Q which is defined as the product of n-1 elementary reflectors H(i) of order n, as returned by CHPTRD using packed storage

SYNOPSIS

SUBROUTINE CUPGTR(
UPLO, N, AP, TAU, Q, LDQ, WORK, INFO )

    
CHARACTER UPLO

    
INTEGER INFO, LDQ, N

    
COMPLEX AP( * ), Q( LDQ, * ), TAU( * ), WORK( * )

PURPOSE

CUPGTR generates a complex unitary matrix Q which is defined as the product of n-1 elementary reflectors H(i) of order n, as returned by CHPTRD 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 CHPTRD; = aqLaq: Lower triangular packed storage used in previous call to CHPTRD.
N (input) INTEGER
The order of the matrix Q. N >= 0.
AP (input) COMPLEX array, dimension (N*(N+1)/2)
The vectors which define the elementary reflectors, as returned by CHPTRD.
TAU (input) COMPLEX array, dimension (N-1)
TAU(i) must contain the scalar factor of the elementary reflector H(i), as returned by CHPTRD.
Q (output) COMPLEX array, dimension (LDQ,N)
The N-by-N unitary matrix Q.
LDQ (input) INTEGER
The leading dimension of the array Q. LDQ >= max(1,N).
WORK (workspace) COMPLEX array, dimension (N-1)
INFO (output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value