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LAPACK
3.7.0
LAPACK: Linear Algebra PACKage
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subroutine ztpcon | ( | character | NORM, |
character | UPLO, | ||
character | DIAG, | ||
integer | N, | ||
complex*16, dimension( * ) | AP, | ||
double precision | RCOND, | ||
complex*16, dimension( * ) | WORK, | ||
double precision, dimension( * ) | RWORK, | ||
integer | INFO | ||
) |
ZTPCON
Download ZTPCON + dependencies [TGZ] [ZIP] [TXT]
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)) ).
[in] | NORM | NORM is CHARACTER*1 Specifies whether the 1-norm condition number or the infinity-norm condition number is required: = '1' or 'O': 1-norm; = 'I': Infinity-norm. |
[in] | UPLO | UPLO is CHARACTER*1 = 'U': A is upper triangular; = 'L': A is lower triangular. |
[in] | DIAG | DIAG is CHARACTER*1 = 'N': A is non-unit triangular; = 'U': A is unit triangular. |
[in] | N | N is INTEGER The order of the matrix A. N >= 0. |
[in] | AP | AP is COMPLEX*16 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 AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(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. |
[out] | RCOND | RCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(norm(A) * norm(inv(A))). |
[out] | WORK | WORK is COMPLEX*16 array, dimension (2*N) |
[out] | RWORK | RWORK is DOUBLE PRECISION array, dimension (N) |
[out] | INFO | INFO is INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value |
Definition at line 132 of file ztpcon.f.