stpmqrt.f man page

stpmqrt.f —

Synopsis

Functions/Subroutines

subroutine stpmqrt (SIDE, TRANS, M, N, K, L, NB, V, LDV, T, LDT, A, LDA, B, LDB, WORK, INFO)
STPMQRT

Function/Subroutine Documentation

subroutine stpmqrt (character SIDE, character TRANS, integer M, integer N, integer K, integer L, integer NB, real, dimension( ldv, * ) V, integer LDV, real, dimension( ldt, * ) T, integer LDT, real, dimension( lda, * ) A, integer LDA, real, dimension( ldb, * ) B, integer LDB, real, dimension( * ) WORK, integer INFO)

STPMQRT

Purpose:

``` STPMQRT applies a real orthogonal matrix Q obtained from a
"triangular-pentagonal" real block reflector H to a general
real matrix C, which consists of two blocks A and B.```
Parameters:

SIDE

```          SIDE is CHARACTER*1
= 'L': apply Q or Q^T from the Left;
= 'R': apply Q or Q^T from the Right.```

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 B. M >= 0.```

N

```          N is INTEGER
The number of columns of the matrix B. N >= 0.```

K

```          K is INTEGER
The number of elementary reflectors whose product defines
the matrix Q.```

L

```          L is INTEGER
The order of the trapezoidal part of V.
K >= L >= 0.  See Further Details.```

NB

```          NB is INTEGER
The block size used for the storage of T.  K >= NB >= 1.
This must be the same value of NB used to generate T
in CTPQRT.```

V

```          V is REAL array, dimension (LDA,K)
The i-th column must contain the vector which defines the
elementary reflector H(i), for i = 1,2,...,k, as returned by
CTPQRT in B.  See Further Details.```

LDV

```          LDV is INTEGER
The leading dimension of the array V.
If SIDE = 'L', LDV >= max(1,M);
if SIDE = 'R', LDV >= max(1,N).```

T

```          T is REAL array, dimension (LDT,K)
The upper triangular factors of the block reflectors
as returned by CTPQRT, stored as a NB-by-K matrix.```

LDT

```          LDT is INTEGER
The leading dimension of the array T.  LDT >= NB.```

A

```          A is REAL array, dimension
(LDA,N) if SIDE = 'L' or
(LDA,K) if SIDE = 'R'
On entry, the K-by-N or M-by-K matrix A.
On exit, A is overwritten by the corresponding block of
Q*C or Q^T*C or C*Q or C*Q^T.  See Further Details.```

LDA

```          LDA is INTEGER
The leading dimension of the array A.
If SIDE = 'L', LDC >= max(1,K);
If SIDE = 'R', LDC >= max(1,M).```

B

```          B is REAL array, dimension (LDB,N)
On entry, the M-by-N matrix B.
On exit, B is overwritten by the corresponding block of
Q*C or Q^T*C or C*Q or C*Q^T.  See Further Details.```

LDB

```          LDB is INTEGER
The leading dimension of the array B.
LDB >= max(1,M).```

WORK

```          WORK is REAL array. The dimension of WORK is
N*NB if SIDE = 'L', or  M*NB 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

NAG Ltd.

Date:

December 2016

Further Details:

```  The columns of the pentagonal matrix V contain the elementary reflectors
H(1), H(2), ..., H(K); V is composed of a rectangular block V1 and a
trapezoidal block V2:

V = [V1]
[V2].

The size of the trapezoidal block V2 is determined by the parameter L,
where 0 <= L <= K; V2 is upper trapezoidal, consisting of the first L
rows of a K-by-K upper triangular matrix.  If L=K, V2 is upper triangular;
if L=0, there is no trapezoidal block, hence V = V1 is rectangular.

If SIDE = 'L':  C = [A]  where A is K-by-N,  B is M-by-N and V is M-by-K.
[B]

If SIDE = 'R':  C = [A B]  where A is M-by-K, B is M-by-N and V is N-by-K.

The real orthogonal matrix Q is formed from V and T.

If TRANS='N' and SIDE='L', C is on exit replaced with Q * C.

If TRANS='T' and SIDE='L', C is on exit replaced with Q^T * C.

If TRANS='N' and SIDE='R', C is on exit replaced with C * Q.

If TRANS='T' and SIDE='R', C is on exit replaced with C * Q^T.```

Definition at line 218 of file stpmqrt.f.

Author

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Referenced By

The man page stpmqrt(3) is an alias of stpmqrt.f(3).

Sat Jun 24 2017 Version 3.7.1 LAPACK