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man pages->IRIX man pages -> complib/ssygst (3)
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### Contents

```
SSYGST(3F)							    SSYGST(3F)

```

### NAME[Toc][Back]

```     SSYGST - reduce a real symmetric-definite generalized eigenproblem	to
standard form
```

### SYNOPSIS[Toc][Back]

```     SUBROUTINE	SSYGST(	ITYPE, UPLO, N,	A, LDA,	B, LDB,	INFO )

CHARACTER	UPLO

INTEGER	INFO, ITYPE, LDA, LDB, N

REAL		A( LDA,	* ), B(	LDB, * )
```

### PURPOSE[Toc][Back]

```     SSYGST reduces a real symmetric-definite generalized eigenproblem to
standard form.

If	ITYPE =	1, the problem is A*x =	lambda*B*x,
and A is overwritten by inv(U**T)*A*inv(U)	or inv(L)*A*inv(L**T)

If	ITYPE =	2 or 3,	the problem is A*B*x = lambda*x	or
B*A*x = lambda*x, and A is	overwritten by U*A*U**T	or L**T*A*L.

B must have been previously factorized as U**T*U or L*L**T	by SPOTRF.

```

### ARGUMENTS[Toc][Back]

```     ITYPE   (input) INTEGER
= 1: compute inv(U**T)*A*inv(U) or	inv(L)*A*inv(L**T);
= 2 or 3: compute U*A*U**T	or L**T*A*L.

UPLO    (input) CHARACTER
= 'U':  Upper triangle of A is stored and B is factored as
U**T*U; = 'L':  Lower triangle of A is stored and B is factored
as	L*L**T.

N	     (input) INTEGER
The order of the matrices A and B.	 N >= 0.

A	     (input/output) REAL array,	dimension (LDA,N)
On	entry, the symmetric matrix A.	If UPLO	= 'U', the leading Nby-N
upper	triangular part	of A contains the upper	triangular
part of the matrix	A, and the strictly lower triangular part of A
is	not referenced.	 If UPLO = 'L',	the leading N-by-N lower
triangular	part of	A contains the lower triangular	part of	the
matrix A, and the strictly	upper triangular part of A is not
referenced.

On	exit, if INFO =	0, the transformed matrix, stored in the same
format as A.

Page 1

SSYGST(3F)							    SSYGST(3F)

LDA     (input) INTEGER
The leading dimension of the array	A.  LDA	>= max(1,N).

B	     (input) REAL array, dimension (LDB,N)
The triangular factor from	the Cholesky factorization of B, as
returned by SPOTRF.

LDB     (input) INTEGER
The leading dimension of the array	B.  LDB	>= max(1,N).

INFO    (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
SSYGST(3F)							    SSYGST(3F)

```

### NAME[Toc][Back]

```     SSYGST - reduce a real symmetric-definite generalized eigenproblem	to
standard form
```

### SYNOPSIS[Toc][Back]

```     SUBROUTINE	SSYGST(	ITYPE, UPLO, N,	A, LDA,	B, LDB,	INFO )

CHARACTER	UPLO

INTEGER	INFO, ITYPE, LDA, LDB, N

REAL		A( LDA,	* ), B(	LDB, * )
```

### PURPOSE[Toc][Back]

```     SSYGST reduces a real symmetric-definite generalized eigenproblem to
standard form.

If	ITYPE =	1, the problem is A*x =	lambda*B*x,
and A is overwritten by inv(U**T)*A*inv(U)	or inv(L)*A*inv(L**T)

If	ITYPE =	2 or 3,	the problem is A*B*x = lambda*x	or
B*A*x = lambda*x, and A is	overwritten by U*A*U**T	or L**T*A*L.

B must have been previously factorized as U**T*U or L*L**T	by SPOTRF.

```

### ARGUMENTS[Toc][Back]

```     ITYPE   (input) INTEGER
= 1: compute inv(U**T)*A*inv(U) or	inv(L)*A*inv(L**T);
= 2 or 3: compute U*A*U**T	or L**T*A*L.

UPLO    (input) CHARACTER
= 'U':  Upper triangle of A is stored and B is factored as
U**T*U; = 'L':  Lower triangle of A is stored and B is factored
as	L*L**T.

N	     (input) INTEGER
The order of the matrices A and B.	 N >= 0.

A	     (input/output) REAL array,	dimension (LDA,N)
On	entry, the symmetric matrix A.	If UPLO	= 'U', the leading Nby-N
upper	triangular part	of A contains the upper	triangular
part of the matrix	A, and the strictly lower triangular part of A
is	not referenced.	 If UPLO = 'L',	the leading N-by-N lower
triangular	part of	A contains the lower triangular	part of	the
matrix A, and the strictly	upper triangular part of A is not
referenced.

On	exit, if INFO =	0, the transformed matrix, stored in the same
format as A.

Page 1

SSYGST(3F)							    SSYGST(3F)

LDA     (input) INTEGER
The leading dimension of the array	A.  LDA	>= max(1,N).

B	     (input) REAL array, dimension (LDB,N)
The triangular factor from	the Cholesky factorization of B, as
returned by SPOTRF.

LDB     (input) INTEGER
The leading dimension of the array	B.  LDB	>= max(1,N).

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

PPPPaaaaggggeeee 2222```
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