Let M = NEVAL, λ = EVAL, xj = EVEC(*, J) , the j-th column of EVEC. Also, let ɛ be the machine precision given by AMACH(4). The performance index, , is defined to be
The norms used are a modified form of the 1-norm. The norm of the complex vector v is
While the exact value of is highly machine dependent, the performance of GVCSP is considered excellent if < 1, good if 1 ≤≤ 100, and poor if > 100.. The performance index was first developed by the EISPACK project at Argonne National Laboratory; see Garbow et al. (1977, pages 77-79).
Comments
1. Workspace may be explicitly provided, if desired, by use of G2ISP/DG2ISP. The reference is: