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upgtr(3) LAPACK upgtr(3)

upgtr - {up,op}gtr: generate Q from hetrd


subroutine cupgtr (uplo, n, ap, tau, q, ldq, work, info)
CUPGTR subroutine dopgtr (uplo, n, ap, tau, q, ldq, work, info)
DOPGTR subroutine sopgtr (uplo, n, ap, tau, q, ldq, work, info)
SOPGTR subroutine zupgtr (uplo, n, ap, tau, q, ldq, work, info)
ZUPGTR

CUPGTR

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 = '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 CHPTRD;
= 'L': Lower triangular packed storage used in previous
call to CHPTRD.

N


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

AP


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

TAU


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

Q


Q is COMPLEX array, dimension (LDQ,N)
The N-by-N unitary matrix Q.

LDQ


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

WORK


WORK is COMPLEX 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.

Definition at line 113 of file cupgtr.f.

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.

Definition at line 113 of file dopgtr.f.

SOPGTR

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 = '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 SSPTRD;
= 'L': Lower triangular packed storage used in previous
call to SSPTRD.

N


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

AP


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

TAU


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

Q


Q is REAL 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 REAL 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.

Definition at line 113 of file sopgtr.f.

ZUPGTR

Purpose:


ZUPGTR 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
ZHPTRD 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 ZHPTRD;
= 'L': Lower triangular packed storage used in previous
call to ZHPTRD.

N


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

AP


AP is COMPLEX*16 array, dimension (N*(N+1)/2)
The vectors which define the elementary reflectors, as
returned by ZHPTRD.

TAU


TAU is COMPLEX*16 array, dimension (N-1)
TAU(i) must contain the scalar factor of the elementary
reflector H(i), as returned by ZHPTRD.

Q


Q is COMPLEX*16 array, dimension (LDQ,N)
The N-by-N unitary matrix Q.

LDQ


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

WORK


WORK is COMPLEX*16 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.

Definition at line 113 of file zupgtr.f.

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