GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
CentOS 4.8 |
i386 |
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ssygst(l) |
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SSYGST - reduce a real symmetric-definite generalized eigenproblem to standard form
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SUBROUTINE SSYGST( |
ITYPE, UPLO, N, A, LDA, B, LDB, INFO ) |
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CHARACTER |
UPLO |
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INTEGER |
INFO, ITYPE, LDA, LDB, N |
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REAL |
A( LDA, * ), B( LDB, * ) |
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.
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 N-by-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.
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
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ssygst(l) | |