dtpcon(3P) Sun Performance Library dtpcon(3P)NAMEdtpcon - estimate the reciprocal of the condition number of a packed
triangular matrix A, in either the 1-norm or the infinity-norm
SYNOPSIS
SUBROUTINE DTPCON(NORM, UPLO, DIAG, N, A, RCOND, WORK, WORK2, INFO)
CHARACTER * 1 NORM, UPLO, DIAG
INTEGER N, INFO
INTEGER WORK2(*)
DOUBLE PRECISION RCOND
DOUBLE PRECISION A(*), WORK(*)
SUBROUTINE DTPCON_64(NORM, UPLO, DIAG, N, A, RCOND, WORK, WORK2,
INFO)
CHARACTER * 1 NORM, UPLO, DIAG
INTEGER*8 N, INFO
INTEGER*8 WORK2(*)
DOUBLE PRECISION RCOND
DOUBLE PRECISION A(*), WORK(*)
F95 INTERFACE
SUBROUTINE TPCON(NORM, UPLO, DIAG, [N], A, RCOND, [WORK], [WORK2],
[INFO])
CHARACTER(LEN=1) :: NORM, UPLO, DIAG
INTEGER :: N, INFO
INTEGER, DIMENSION(:) :: WORK2
REAL(8) :: RCOND
REAL(8), DIMENSION(:) :: A, WORK
SUBROUTINE TPCON_64(NORM, UPLO, DIAG, [N], A, RCOND, [WORK], [WORK2],
[INFO])
CHARACTER(LEN=1) :: NORM, UPLO, DIAG
INTEGER(8) :: N, INFO
INTEGER(8), DIMENSION(:) :: WORK2
REAL(8) :: RCOND
REAL(8), DIMENSION(:) :: A, WORK
C INTERFACE
#include <sunperf.h>
void dtpcon(char norm, char uplo, char diag, int n, double *a, double
*rcond, int *info);
void dtpcon_64(char norm, char uplo, char diag, long n, double *a, dou‐
ble *rcond, long *info);
PURPOSEdtpcon estimates the reciprocal of the condition number of a packed
triangular matrix A, in either the 1-norm or the infinity-norm.
The norm of A is computed and an estimate is obtained for norm(inv(A)),
then the reciprocal of the condition number is computed as
RCOND = 1 / ( norm(A) * norm(inv(A)) ).
ARGUMENTS
NORM (input)
Specifies whether the 1-norm condition number or the infin‐
ity-norm condition number is required:
= '1' or 'O': 1-norm;
= 'I': Infinity-norm.
UPLO (input)
= 'U': A is upper triangular;
= 'L': A is lower triangular.
DIAG (input)
= 'N': A is non-unit triangular;
= 'U': A is unit triangular.
N (input) The order of the matrix A. N >= 0.
A (input) DOUBLE PRECISION array, dimension (N*(N+1)/2)
The upper or lower triangular matrix A, packed columnwise in
a linear array. The j-th column of A is stored in the array
A as follows: if UPLO = 'U', A(i + (j-1)*j/2) = A(i,j) for
1<=i<=j; if UPLO = 'L', A(i + (j-1)*(2n-j)/2) = A(i,j) for
j<=i<=n. If DIAG = 'U', the diagonal elements of A are not
referenced and are assumed to be 1.
RCOND (output)
The reciprocal of the condition number of the matrix A, com‐
puted as RCOND = 1/(norm(A) * norm(inv(A))).
WORK (workspace)
DOUBLE PRECISION array, dimension(3*N)
WORK2 (workspace)
INTEGER array, dimension(N)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value
6 Mar 2009 dtpcon(3P)
