dpttrf
dpttrf - compute the L*D*L' factorization of a real symmetric positive definite tridiagonal matrix A
SUBROUTINE DPTTRF( N, DIAG, OFFD, INFO)
INTEGER N, INFO
DOUBLE PRECISION DIAG(*), OFFD(*)
SUBROUTINE DPTTRF_64( N, DIAG, OFFD, INFO)
INTEGER*8 N, INFO
DOUBLE PRECISION DIAG(*), OFFD(*)
SUBROUTINE PTTRF( [N], DIAG, OFFD, [INFO])
INTEGER :: N, INFO
REAL(8), DIMENSION(:) :: DIAG, OFFD
SUBROUTINE PTTRF_64( [N], DIAG, OFFD, [INFO])
INTEGER(8) :: N, INFO
REAL(8), DIMENSION(:) :: DIAG, OFFD
#include <sunperf.h>
void dpttrf(int n, double *diag, double *offd, int *info);
void dpttrf_64(long n, double *diag, double *offd, long *info);
dpttrf computes the L*D*L' factorization of a real symmetric
positive definite tridiagonal matrix A. The factorization may also
be regarded as having the form A = U'*D*U.
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* N (input)
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The order of the matrix A. N >= 0.
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* DIAG (input/output)
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On entry, the n diagonal elements of the tridiagonal matrix
A. On exit, the n diagonal elements of the diagonal matrix
DIAG from the L*DIAG*L' factorization of A.
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* OFFD (input/output)
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On entry, the (n-1) subdiagonal elements of the tridiagonal
matrix A. On exit, the (n-1) subdiagonal elements of the
unit bidiagonal factor L from the L*DIAG*L' factorization of A.
OFFD can also be regarded as the superdiagonal of the unit
bidiagonal factor U from the U'*DIAG*U factorization of A.
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* INFO (output)
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