Real Nonsymmetric Drivers

    There are six drivers for nonsymmetric eigenvalues problem. They are named in the form of XndrvY, where the first character X specifies the precision used,

s single precision

d double precision

and the last character Y is a number between 1 and 6 indicating the mode to be used. Each number is associated with a combination of bmat and iparam(7) parameters used in that driver and also on whether the desired shift is real or complex. The parameter which used to select the eigenvalues of interest is controlled by the user, but recommended settings are given in the discussion that follows. Table A.4 summarizes the features of the double precision drivers. The first four drivers are the ones most commonly used. The last two drivers are used when the complex shift used in the shift-invert mode has a nonzero imaginary part. Either dndrv5 or dndrv6 may be modified to solve a standard eigenvalue problem in shift-invert mode with a complex shift. If the amount of storage used by complex arithmetic is not prohibitive, then the complex drivers of  A.3 should be used instead. A procedure for modifying a nonsymmetric driver is outlined below. It is similar to the one used for the symmetric drivers.

 

DRIVER PROBLEM SOLVED

dndrv1 Standard eigenvalue problem (bmat = 'I') in the regular mode (iparam(7) = 1) No shift is needed in this driver.

dndrv2 Standard eigenvalue problem (bmat = 'I') in a shift-invert mode (iparam(7) = 3) The shift is real (sigmai = 0.0).

dndrv3 Generalized eigenvalue problem (bmat = 'G') in the regular inverse mode (iparam(7) = 2) No shift is needed in this driver.

dndrv4 Generalized eigenvalue problem (bmat = 'G') in a shift-invert mode (iparam(7) = 3) with a real shift (sigmai = 0.0).

dndrv5 Generalized eigenvalue problem (bmat = 'G') in a shift invert mode (iparam(7) = 3) The shift has a nonzero imaginary part (sigmai 0.)

dndrv6 Solve a generalized eigenvalue problem (bmat = 'G') in a shift invert mode (iparam(7) = 4) The shift has a nonzero imaginary part (sigmai 0).