iparmq

Functions

INT iparmq(
    const INT   ispec,
    const char* name,
    const char* opts,
    const INT   n,
    const INT   ilo,
    const INT   ihi,
    const INT   lwork
);

INT iparmq(const INT ispec, const char *name, const char *opts, const INT n, const INT ilo, const INT ihi, const INT lwork)

IPARMQ returns problem and machine dependent parameters useful for xHSEQR and related subroutines for eigenvalue problems.

Parameters

in

ispec

Specifies which tunable parameter to return: = 12: (INMIN) Matrices of order nmin or less are sent directly to xLAHQR. NMIN must be at least 11. = 13: (INWIN) Size of the deflation window. = 14: (INIBL) Determines when to stop nibbling and invest in an (expensive) multi-shift QR sweep. = 15: (NSHFTS) The number of simultaneous shifts in a multi-shift QR iteration. = 16: (IACC22) Whether to accumulate reflections before updating far-from-diagonal elements (0, 1, or 2). = 17: (ICOST) Relative cost of flops within the near-the-diagonal shift chase vs BLAS calls.

in

name

Name of the calling subroutine.

in

opts

Concatenation of the string arguments to TTQRE.

in

n

Order of the Hessenberg matrix H.

in

ilo

It is assumed that H is already upper triangular in rows and columns 0:ilo-1 (0-based).

in

ihi

It is assumed that H is already upper triangular in rows and columns ihi+1:n-1 (0-based).

in

lwork

The amount of workspace available.