Contents
ztpcon - estimate the reciprocal of the condition number of
a packed triangular matrix A, in either the 1-norm or the
infinity-norm
SUBROUTINE ZTPCON(NORM, UPLO, DIAG, N, A, RCOND, WORK, WORK2, INFO)
CHARACTER * 1 NORM, UPLO, DIAG
DOUBLE COMPLEX A(*), WORK(*)
INTEGER N, INFO
DOUBLE PRECISION RCOND
DOUBLE PRECISION WORK2(*)
SUBROUTINE ZTPCON_64(NORM, UPLO, DIAG, N, A, RCOND, WORK, WORK2,
INFO)
CHARACTER * 1 NORM, UPLO, DIAG
DOUBLE COMPLEX A(*), WORK(*)
INTEGER*8 N, INFO
DOUBLE PRECISION RCOND
DOUBLE PRECISION WORK2(*)
F95 INTERFACE
SUBROUTINE TPCON(NORM, UPLO, DIAG, N, A, RCOND, [WORK], [WORK2],
[INFO])
CHARACTER(LEN=1) :: NORM, UPLO, DIAG
COMPLEX(8), DIMENSION(:) :: A, WORK
INTEGER :: N, INFO
REAL(8) :: RCOND
REAL(8), DIMENSION(:) :: WORK2
SUBROUTINE TPCON_64(NORM, UPLO, DIAG, N, A, RCOND, [WORK], [WORK2],
[INFO])
CHARACTER(LEN=1) :: NORM, UPLO, DIAG
COMPLEX(8), DIMENSION(:) :: A, WORK
INTEGER(8) :: N, INFO
REAL(8) :: RCOND
REAL(8), DIMENSION(:) :: WORK2
C INTERFACE
#include <sunperf.h>
void ztpcon(char norm, char uplo, char diag, int n, doub-
lecomplex *a, double *rcond, int *info);
void ztpcon_64(char norm, char uplo, char diag, long n,
doublecomplex *a, double *rcond, long *info);
ztpcon 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)) ).
NORM (input)
Specifies whether the 1-norm condition number or
the infinity-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) 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, computed as RCOND = 1/(norm(A) *
norm(inv(A))).
WORK (workspace)
dimension(2*N)
WORK2 (workspace)
dimension(N)
INFO (output)
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an ille-
gal value