LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

Go to the source code of this file.
Functions/Subroutines  
subroutine  dtpcon (NORM, UPLO, DIAG, N, AP, RCOND, WORK, IWORK, INFO) 
DTPCON 
subroutine dtpcon  (  character  NORM, 
character  UPLO,  
character  DIAG,  
integer  N,  
double precision, dimension( * )  AP,  
double precision  RCOND,  
double precision, dimension( * )  WORK,  
integer, dimension( * )  IWORK,  
integer  INFO  
) 
DTPCON
Download DTPCON + dependencies [TGZ] [ZIP] [TXT]DTPCON estimates the reciprocal of the condition number of a packed triangular matrix A, in either the 1norm or the infinitynorm. 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 1norm condition number or the infinitynorm condition number is required: = '1' or 'O': 1norm; = 'I': Infinitynorm. 
[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 nonunit triangular; = 'U': A is unit triangular. 
[in]  N  N is INTEGER The order of the matrix A. N >= 0. 
[in]  AP  AP is DOUBLE PRECISION array, dimension (N*(N+1)/2) The upper or lower triangular matrix A, packed columnwise in a linear array. The jth column of A is stored in the array AP as follows: if UPLO = 'U', AP(i + (j1)*j/2) = A(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j1)*(2nj)/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 DOUBLE PRECISION array, dimension (3*N) 
[out]  IWORK  IWORK is INTEGER array, dimension (N) 
[out]  INFO  INFO is INTEGER = 0: successful exit < 0: if INFO = i, the ith argument had an illegal value 
Definition at line 130 of file dtpcon.f.