Zgbcon Zgbtrf Zgbtrs Zgecon Zgetrf Zgetri Zgetrs Zgtcon Zgttrf Zgttrs Zspcon Zsptrf Zsptri Zsptrs Zsycon Zsytrf Zsytri Zsytrs

Zsycon() Sub Zsycon ( Uplo As  String, N As  Long, A() As  Complex, IPiv() As  Long, ANorm As  Double, RCond As  Double, Info As  Long  ) Condition number of a complex symmetric matrix Purpose This routine estimates the reciprocal of the condition number (in the 1-norm) of a complex symmetric matrix A using the factorization A = U*D*U^T or A = L*D*L^T computed by Zsytrf. An estimate is obtained for norm(inv(A)), and the reciprocal of the condition number is computed as RCond = 1 / (norm(A) * norm(inv(A))). Parameters [in] Uplo 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. [in] N Order of the matrix A. (N >= 0) (If N = 0, returns RCond = 1) [in] A() Array A(LA1 - 1, LA2 - 1) (LA1 >= N, LA2 >= N) The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by Zsytrf. [in] IPiv() Array IPiv(LIPiv - 1) (LIPiv >= N) Details of the interchanges and the block structure of D as determined by Zsytrf. [in] ANorm The 1-norm of the original matrix A. (ANorm >= 0) [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] 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 A() is invalid. = -4: The argument IPiv() is invalid. = -5: The argument ANorm had an illegal value. (ANorm < 0) Reference LAPACK Example Program See example of Zsysv.