·  Home
+   man pages
 -> Linux -> FreeBSD -> OpenBSD -> NetBSD -> Tru64 Unix -> HP-UX 11i -> IRIX
·  Linux HOWTOs
·  FreeBSD Tips
·  *niX Forums

man pages->IRIX man pages -> complib/sgeql2 (3)
 Title
 Content
 Arch
 Section All Sections 1 - General Commands 2 - System Calls 3 - Subroutines 4 - Special Files 5 - File Formats 6 - Games 7 - Macros and Conventions 8 - Maintenance Commands 9 - Kernel Interface n - New Commands

### Contents

```
SGEQL2(3F)							    SGEQL2(3F)

```

### NAME[Toc][Back]

```     SGEQL2 - compute a	QL factorization of a real m by	n matrix A
```

### SYNOPSIS[Toc][Back]

```     SUBROUTINE	SGEQL2(	M, N, A, LDA, TAU, WORK, INFO )

INTEGER	INFO, LDA, M, N

REAL		A( LDA,	* ), TAU( * ), WORK( * )
```

### PURPOSE[Toc][Back]

```     SGEQL2 computes a QL factorization	of a real m by n matrix	A:  A =	Q * L.

```

### ARGUMENTS[Toc][Back]

```     M	     (input) INTEGER
The number	of rows	of the matrix A.  M >= 0.

N	     (input) INTEGER
The number	of columns of the matrix A.  N >= 0.

A	     (input/output) REAL array,	dimension (LDA,N)
On	entry, the m by	n matrix A.  On	exit, if m >= n, the lower
triangle of the subarray A(m-n+1:m,1:n) contains the n by n lower
triangular	matrix L; if m <= n, the elements on and below the
(n-m)-th superdiagonal contain the	m by n lower trapezoidal
matrix L; the remaining elements, with the	array TAU, represent
the orthogonal matrix Q as	a product of elementary	reflectors
(see Further Details).  LDA     (input) INTEGER The leading
dimension of the array A.	LDA >= max(1,M).

TAU     (output) REAL array, dimension (min(M,N))
The scalar	factors	of the elementary reflectors (see Further
Details).

WORK    (workspace) REAL array, dimension (N)

INFO    (output) INTEGER
= 0: successful exit
< 0: if INFO = -i,	the i-th argument had an illegal value

FURTHER	DETAILS
The matrix	Q is represented as a product of elementary reflectors

Q = H(k) . . . H(2) H(1), where	k = min(m,n).

Each H(i) has the form

H(i) = I - tau * v * v'

where tau is a real scalar, and v is a real vector	with
v(m-k+i+1:m) = 0 and v(m-k+i) = 1;	v(1:m-k+i-1) is	stored on exit in

Page 1

SGEQL2(3F)							    SGEQL2(3F)

A(1:m-k+i-1,n-k+i), and tau in TAU(i).
SGEQL2(3F)							    SGEQL2(3F)

```

### NAME[Toc][Back]

```     SGEQL2 - compute a	QL factorization of a real m by	n matrix A
```

### SYNOPSIS[Toc][Back]

```     SUBROUTINE	SGEQL2(	M, N, A, LDA, TAU, WORK, INFO )

INTEGER	INFO, LDA, M, N

REAL		A( LDA,	* ), TAU( * ), WORK( * )
```

### PURPOSE[Toc][Back]

```     SGEQL2 computes a QL factorization	of a real m by n matrix	A:  A =	Q * L.

```

### ARGUMENTS[Toc][Back]

```     M	     (input) INTEGER
The number	of rows	of the matrix A.  M >= 0.

N	     (input) INTEGER
The number	of columns of the matrix A.  N >= 0.

A	     (input/output) REAL array,	dimension (LDA,N)
On	entry, the m by	n matrix A.  On	exit, if m >= n, the lower
triangle of the subarray A(m-n+1:m,1:n) contains the n by n lower
triangular	matrix L; if m <= n, the elements on and below the
(n-m)-th superdiagonal contain the	m by n lower trapezoidal
matrix L; the remaining elements, with the	array TAU, represent
the orthogonal matrix Q as	a product of elementary	reflectors
(see Further Details).  LDA     (input) INTEGER The leading
dimension of the array A.	LDA >= max(1,M).

TAU     (output) REAL array, dimension (min(M,N))
The scalar	factors	of the elementary reflectors (see Further
Details).

WORK    (workspace) REAL array, dimension (N)

INFO    (output) INTEGER
= 0: successful exit
< 0: if INFO = -i,	the i-th argument had an illegal value

FURTHER	DETAILS
The matrix	Q is represented as a product of elementary reflectors

Q = H(k) . . . H(2) H(1), where	k = min(m,n).

Each H(i) has the form

H(i) = I - tau * v * v'

where tau is a real scalar, and v is a real vector	with
v(m-k+i+1:m) = 0 and v(m-k+i) = 1;	v(1:m-k+i-1) is	stored on exit in

Page 1

SGEQL2(3F)							    SGEQL2(3F)

A(1:m-k+i-1,n-k+i), and tau in TAU(i).

PPPPaaaaggggeeee 2222```
[ Back ]
Similar pages
 Name OS Title dgeqr2 IRIX compute a QR factorization of a real m by n matrix A sgeqlf IRIX compute a QL factorization of a real M-by-N matrix A dgerqf IRIX compute an RQ factorization of a real M-by-N matrix A dgerq2 IRIX compute an RQ factorization of a real m by n matrix A sgeqrf IRIX compute a QR factorization of a real M-by-N matrix A sgerq2 IRIX compute an RQ factorization of a real m by n matrix A sgerqf IRIX compute an RQ factorization of a real M-by-N matrix A dgeqrf IRIX compute a QR factorization of a real M-by-N matrix A dgeqlf IRIX compute a QL factorization of a real M-by-N matrix A sgeqr2 IRIX compute a QR factorization of a real m by n matrix A