sget31.f - Man Page

subroutine sget31 (rmax, lmax, ninfo, knt)
SGET31

SGET31

Purpose:

 SGET31 tests SLALN2, a routine for solving

    (ca A - w D)X = sB

 where A is an NA by NA matrix (NA=1 or 2 only), w is a real (NW=1) or
 complex (NW=2) constant, ca is a real constant, D is an NA by NA real
 diagonal matrix, and B is an NA by NW matrix (when NW=2 the second
 column of B contains the imaginary part of the solution).  The code
 returns X and s, where s is a scale factor, less than or equal to 1,
 which is chosen to avoid overflow in X.

 If any singular values of ca A-w D are less than another input
 parameter SMIN, they are perturbed up to SMIN.

 The test condition is that the scaled residual

     norm( (ca A-w D)*X - s*B ) /
           ( max( ulp*norm(ca A-w D), SMIN )*norm(X) )

 should be on the order of 1.  Here, ulp is the machine precision.
 Also, it is verified that SCALE is less than or equal to 1, and that
 XNORM = infinity-norm(X).

Parameters

RMAX

          RMAX is REAL
          Value of the largest test ratio.

LMAX

          LMAX is INTEGER
          Example number where largest test ratio achieved.

NINFO

          NINFO is INTEGER array, dimension (2)
          NINFO(1) = number of examples with INFO less than 0
          NINFO(2) = number of examples with INFO greater than 0

KNT

          KNT is INTEGER
          Total number of examples tested.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 90 of file sget31.f.