LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  dppcon (UPLO, N, AP, ANORM, RCOND, WORK, IWORK, INFO) 
DPPCON 
subroutine dppcon  (  character  UPLO, 
integer  N,  
double precision, dimension( * )  AP,  
double precision  ANORM,  
double precision  RCOND,  
double precision, dimension( * )  WORK,  
integer, dimension( * )  IWORK,  
integer  INFO  
) 
DPPCON
Download DPPCON + dependencies [TGZ] [ZIP] [TXT]DPPCON estimates the reciprocal of the condition number (in the 1norm) of a real symmetric positive definite packed matrix using the Cholesky factorization A = U**T*U or A = L*L**T computed by DPPTRF. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
[in]  UPLO  UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored. 
[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 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 jth column of U or L is stored in the array AP as follows: if UPLO = 'U', AP(i + (j1)*j/2) = U(i,j) for 1<=i<=j; if UPLO = 'L', AP(i + (j1)*(2nj)/2) = L(i,j) for j<=i<=n. 
[in]  ANORM  ANORM is DOUBLE PRECISION The 1norm (or infinitynorm) of the symmetric matrix A. 
[out]  RCOND  RCOND is DOUBLE PRECISION The reciprocal of the condition number of the matrix A, computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an estimate of the 1norm of inv(A) computed in this routine. 
[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 119 of file dppcon.f.