ssytrf
ssytrf - compute the factorization of a real symmetric matrix A using the Bunch-Kaufman diagonal pivoting method
SUBROUTINE SSYTRF( UPLO, N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDA, LDWORK, INFO
INTEGER IPIVOT(*)
REAL A(LDA,*), WORK(*)
SUBROUTINE SSYTRF_64( UPLO, N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDA, LDWORK, INFO
INTEGER*8 IPIVOT(*)
REAL A(LDA,*), WORK(*)
SUBROUTINE SYTRF( UPLO, N, A, [LDA], IPIVOT, [WORK], [LDWORK], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDA, LDWORK, INFO
INTEGER, DIMENSION(:) :: IPIVOT
REAL, DIMENSION(:) :: WORK
REAL, DIMENSION(:,:) :: A
SUBROUTINE SYTRF_64( UPLO, N, A, [LDA], IPIVOT, [WORK], [LDWORK],
* [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDA, LDWORK, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT
REAL, DIMENSION(:) :: WORK
REAL, DIMENSION(:,:) :: A
#include <sunperf.h>
void ssytrf(char uplo, int n, float *a, int lda, int *ipivot, int *info);
void ssytrf_64(char uplo, long n, float *a, long lda, long *ipivot, long *info);
ssytrf computes the factorization of a real symmetric matrix A using
the Bunch-Kaufman diagonal pivoting method. The form of the
factorization is
A = U*D*U**T or A = L*D*L**T
where U (or L) is a product of permutation and unit upper (lower)
triangular matrices, and D is symmetric and block diagonal with
1-by-1 and 2-by-2 diagonal blocks.
This is the blocked version of the algorithm, calling Level 3 BLAS.
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* UPLO (input)
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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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* IPIVOT (output)
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Details of the interchanges and the block structure of D.
If IPIVOT(k) > 0, then rows and columns k and IPIVOT(k) were
interchanged and D(k,k) is a 1-by-1 diagonal block.
If UPLO = 'U' and IPIVOT(k) = IPIVOT(k-1) < 0, then rows and
columns k-1 and -IPIVOT(k) were interchanged and D(k-1:k,k-1:k)
is a 2-by-2 diagonal block. If UPLO = 'L' and IPIVOT(k) =
IPIVOT(k+1) < 0, then rows and columns k+1 and -IPIVOT(k) were
interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block.
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* WORK (workspace)
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On exit, if INFO = 0, WORK(1) returns the optimal LDWORK.
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* LDWORK (input)
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The length of WORK. LDWORK >=1. For best performance
LDWORK >= N*NB, where NB is the block size returned by ILAENV.
If LDWORK = -1, then a workspace query is assumed; the routine
only calculates the optimal size of the WORK array, returns
this value as the first entry of the WORK array, and no error
message related to LDWORK is issued by XERBLA.
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* INFO (output)
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