ssytd2
ssytd2 - reduce a real symmetric matrix A to symmetric tridiagonal form T by an orthogonal similarity transformation
SUBROUTINE SSYTD2( UPLO, N, A, LDA, D, E, TAU, INFO)
CHARACTER * 1 UPLO
INTEGER N, LDA, INFO
REAL A(LDA,*), D(*), E(*), TAU(*)
SUBROUTINE SSYTD2_64( UPLO, N, A, LDA, D, E, TAU, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, LDA, INFO
REAL A(LDA,*), D(*), E(*), TAU(*)
SUBROUTINE SYTD2( UPLO, N, A, [LDA], D, E, TAU, [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, LDA, INFO
REAL, DIMENSION(:) :: D, E, TAU
REAL, DIMENSION(:,:) :: A
SUBROUTINE SYTD2_64( UPLO, N, A, [LDA], D, E, TAU, [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, LDA, INFO
REAL, DIMENSION(:) :: D, E, TAU
REAL, DIMENSION(:,:) :: A
#include <sunperf.h>
void ssytd2(char uplo, int n, float *a, int lda, float *d, float *e, float *tau, int *info);
void ssytd2_64(char uplo, long n, float *a, long lda, float *d, float *e, float *tau, long *info);
ssytd2 reduces a real symmetric matrix A to symmetric tridiagonal
form T by an orthogonal similarity transformation: Q' * A * Q = T.
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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)
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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, if UPLO = 'U', the diagonal and first superdiagonal
of A are overwritten by the corresponding elements of the
tridiagonal matrix T, and the elements above the first
superdiagonal, with the array TAU, represent the orthogonal
matrix Q as a product of elementary reflectors; if UPLO
-
* LDA (input)
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The leading dimension of the array A. LDA >= max(1,N).
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* D (output)
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The diagonal elements of the tridiagonal matrix T:
D(i) = A(i,i).
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* E (output)
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The off-diagonal elements of the tridiagonal matrix T:
E(i) = A(i,i+1) if UPLO = 'U', E(i) = A(i+1,i) if UPLO = 'L'.
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* TAU (output)
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The scalar factors of the elementary reflectors (see Further
Details).
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* INFO (output)
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