ZSPCON
Modified to call ZLACN2 in place of ZLACON, 10 Feb 03, SJH.
Purpose
ZSPCON estimates the reciprocal of the condition number (in the
1-norm) of a complex symmetric packed matrix A using the
factorization A = U*D*U**T or A = L*D*L**T computed by ZSPTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
1-norm) of a complex symmetric packed matrix A using the
factorization A = U*D*U**T or A = L*D*L**T computed by ZSPTRF.
An estimate is obtained for norm(inv(A)), and the reciprocal of the
condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))).
Arguments
| UPLO |
(input) CHARACTER*1
Specifies whether the details of the factorization are stored
as an upper or lower triangular matrix. = 'U': Upper triangular, form is A = U*D*U**T; = 'L': Lower triangular, form is A = L*D*L**T. |
| N |
(input) INTEGER
The order of the matrix A. N >= 0.
|
| AP |
(input) COMPLEX*16 array, dimension (N*(N+1)/2)
The block diagonal matrix D and the multipliers used to
obtain the factor U or L as computed by ZSPTRF, stored as a packed triangular matrix. |
| IPIV |
(input) INTEGER array, dimension (N)
Details of the interchanges and the block structure of D
as determined by ZSPTRF. |
| ANORM |
(input) DOUBLE PRECISION
The 1-norm of the original matrix A.
|
| RCOND |
(output) 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 1-norm of inv(A) computed in this routine. |
| WORK |
(workspace) COMPLEX*16 array, dimension (2*N)
|
| INFO |
(output) INTEGER
= 0: successful exit
< 0: if INFO = -i, the i-th argument had an illegal value |