ssytf2
ssytf2 - compute the factorization of a real symmetric matrix A using the Bunch-Kaufman diagonal pivoting method
SUBROUTINE SSYTF2( UPLO, N, A, LDA, IPIV, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDA, INFO
INTEGER IPIV(*)
REAL A(LDA,*)
SUBROUTINE SSYTF2_64( UPLO, N, A, LDA, IPIV, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDA, INFO
INTEGER*8 IPIV(*)
REAL A(LDA,*)
SUBROUTINE SYTF2( UPLO, [N], A, [LDA], IPIV, [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDA, INFO
INTEGER, DIMENSION(:) :: IPIV
REAL, DIMENSION(:,:) :: A
SUBROUTINE SYTF2_64( UPLO, [N], A, [LDA], IPIV, [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDA, INFO
INTEGER(8), DIMENSION(:) :: IPIV
REAL, DIMENSION(:,:) :: A
#include <sunperf.h>
void ssytf2(char uplo, int n, float *a, int lda, int *ipiv, int *info);
void ssytf2_64(char uplo, long n, float *a, long lda, long *ipiv, long *info);
ssytf2 computes the factorization of a real symmetric matrix A using
the Bunch-Kaufman diagonal pivoting method:
A = U*D*U' or A = L*D*L'
where U (or L) is a product of permutation and unit upper (lower)
triangular matrices, U' is the transpose of U, and D is symmetric and
block diagonal with 1-by-1 and 2-by-2 diagonal blocks.
This is the unblocked version of the algorithm, calling Level 2 BLAS.
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* UPLO (input)
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Specifies whether the upper or lower triangular part of the
symmetric matrix A is stored:
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* N (input)
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The order of the matrix A. N >= 0.
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* A (input/output)
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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, the block diagonal matrix D and the multipliers used
to obtain the factor U or L (see below for further details).
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* LDA (input)
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The leading dimension of the array A. LDA >= max(1,N).
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* IPIV (output)
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Details of the interchanges and the block structure of D.
If IPIV(k) > 0, then rows and columns k and IPIV(k) were
interchanged and D(k,k) is a 1-by-1 diagonal block.
If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, then rows and
columns k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k)
is a 2-by-2 diagonal block. If UPLO = 'L' and IPIV(k) =
IPIV(k+1) < 0, then rows and columns k+1 and -IPIV(k) were
interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block.
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* INFO (output)
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