Computational Modes for Real Symmetric Problems

The reverse communication interface subroutine for symmetric eigenvalue problems is dsaupd . The subroutine is called as shown in Figure 3.4. The argument which may be any one of the settings listed in Table 3.3.

  

Figure 3.4: Calling the ARPACK subroutine dsaupd.

  call dsaupd (ido, bmat, n, which, nev, tol, resid, ncv, v,
 &             ldv, iparam, ipntr, workd, workl, lworkl, info)

 

1|cWHICH 1c|DESCRIPTION

`LA' Largest algebraic eigenvalues.

`SA' Smallest algebraic eigenvalues.

`LM' Eigenvalues largest in magnitude.

`SM' Eigenvalues smallest in magnitude.

`BE' Compute nev eigenvalues, half from each end of the spectrum. When nev is odd, compute one more from the high end than from the low end.

The following is a list of the spectral transformation options for symmetric eigenvalue problems. In the following list, the specification of OP and are given for the various modes. Also, the iparam(7) and bmat settings are listed along with the name of the sample driver for the given mode. Sample drivers for the following modes may be found in the EXAMPLES/SYM subdirectory.  

1.

Regular mode (iparam(7) = 1, bmat = 'I' ). Use driver dsdrv1.

(a)

Solve in regular mode.

(b)

and

2.

Shift-invert mode (iparam(7) = 3, bmat = 'I'). Use driver dsdrv2.

(a)

Solve in shift-invert mode.

(b)

and

3.

Regular inverse mode (iparam(7) = 2, bmat = 'G'). Use driver dsdrv3.

(a)

Solve ${\bf A}{\bf x}={\bf M}{\bf x}\lambda$ in regular inverse mode.

(b)

and

4.

Shift-invert mode (iparam(7) = 3, bmat = 'G'). Use driver dsdrv4.

(a)

Solve ${\bf A}{\bf x}={\bf M}{\bf x}\lambda$ in shift-invert mode.

(b)

and

5.

Buckling mode (iparam(7) = 4, bmat = 'G' ). Use driver dsdrv5.

(a)

Solve in Buckling mode.

(b)

and

6.

Cayley mode (iparam(7) = 5, bmat = 'G' ). Use driver dsdrv6.

(a)

Solve ${\bf A}{\bf x}={\bf M}{\bf x}\lambda$ in Cayley mode.

(b)

and