dppcon
dppcon - estimate the reciprocal of the condition number (in the 1-norm) of a real symmetric positive definite packed matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by SPPTRF
SUBROUTINE DPPCON( UPLO, N, A, ANORM, RCOND, WORK, WORK2, INFO)
CHARACTER * 1 UPLO
INTEGER N, INFO
INTEGER WORK2(*)
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION A(*), WORK(*)
SUBROUTINE DPPCON_64( UPLO, N, A, ANORM, RCOND, WORK, WORK2, INFO)
CHARACTER * 1 UPLO
INTEGER*8 N, INFO
INTEGER*8 WORK2(*)
DOUBLE PRECISION ANORM, RCOND
DOUBLE PRECISION A(*), WORK(*)
SUBROUTINE PPCON( UPLO, N, A, ANORM, RCOND, [WORK], [WORK2], [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER :: N, INFO
INTEGER, DIMENSION(:) :: WORK2
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: A, WORK
SUBROUTINE PPCON_64( UPLO, N, A, ANORM, RCOND, [WORK], [WORK2],
* [INFO])
CHARACTER(LEN=1) :: UPLO
INTEGER(8) :: N, INFO
INTEGER(8), DIMENSION(:) :: WORK2
REAL(8) :: ANORM, RCOND
REAL(8), DIMENSION(:) :: A, WORK
#include <sunperf.h>
void dppcon(char uplo, int n, double *a, double anorm, double *rcond, int *info);
void dppcon_64(char uplo, long n, double *a, double anorm, double *rcond, long *info);
dppcon estimates the reciprocal of the condition number (in the
1-norm) of a real symmetric positive definite packed matrix using
the Cholesky factorization A = U**T*U or A = L*L**T computed by
SPPTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
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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)
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The triangular factor U or L from the Cholesky factorization
A = U**T*U or A = L*L**T, packed columnwise in a linear
array. The j-th column of U or L is stored in the array A
as follows:
if UPLO = 'U', A(i + (j-1)*j/2) = U(i,j) for 1<=i<=j;
if UPLO = 'L', A(i + (j-1)*(2n-j)/2) = L(i,j) for j<=i<=n.
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* ANORM (input)
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The 1-norm (or infinity-norm) of the symmetric matrix A.
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* RCOND (output)
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The reciprocal of the condition number of the matrix A,
computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
estimate of the 1-norm of inv(A) computed in this routine.
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* WORK (workspace)
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dimension(2*N)
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* WORK2 (workspace)
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* INFO (output)
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