zpbcon zpbtrf zpbtrs zptcon zpttrf zpttrs

zpbcon() void zpbcon ( char  uplo, int  n, int  kd, int  ldab, doublecomplex  ab[], double  anorm, double *  rcond, doublecomplex  work[], double  rwork[], int *  info  ) Condition number of a Hermitian positive definite band matrix Purpose This routine estimates the reciprocal of the condition number (in the 1-norm) of a Hermitian positive definite band matrix using the Cholesky factorization A = U^H*U or A = L*L^H computed by zpbtrf. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as rcond = 1 / (anorm * norm(inv(A))). Parameters [in] uplo = 'U': Upper triangular factor U is stored in ab[][]. = 'L': Lower triangular factor L is stored in ab[][]. [in] n Order of the matrix A. (n >= 0) (If n = 0, returns rcond = 1) [in] kd Number of super-diagonals of the matrix A if uplo = 'U', or number of sub-diagonals if uplo = 'L'. (kd >= 0) [in] ldab Leading dimension of the two dimensional array ab[][]. (ldab >= kd + 1) [in] ab[][] Array ab[lab][ldab] (lab >= n) The triangular factor U or L from the Cholesky factorization A = U^H*U or A = L*L^H of the Hermitian positive definite band matrix A, stored in kd+1 x n symmetric band matrix form. [in] anorm The 1-norm (or infinity-norm) of the Hermitian positive definite band matrix A. [out] rcond 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. [out] work[] Array work[lwork] (lwork >= 2*n) Work array. [out] rwork[] Array rwork[lrwork] (lrwork >= n) Work array. [out] info = 0: Successful exit = -1: The argument uplo had an illegal value (uplo != 'U' nor 'L') = -2: The argument n had an illegal value (n < 0) = -3: The argument kd had an illegal value (kd < 0) = -4: The argument ldab had an illegal value (ldab < kd+1) = -6: The argument anorm had an illegal value (anorm < 0) Reference LAPACK