TESTING/EIG/dsyl01.f(3)

NAME
TESTING/EIG/dsyl01.f

SYNOPSIS

  Functions/Subroutines
subroutine dsyl01 (thresh, nfail, rmax, ninfo, knt)
DSYL01

Function/Subroutine Documentation

  subroutine dsyl01 (double precision thresh, integer, dimension( 3 ) nfail, double precision, dimension( 2 ) rmax, integer, dimension( 2 ) ninfo, integer knt)

DSYL01

Purpose:

     DSYL01 tests DTRSYL and DTRSYL3, routines for solving the Sylvester matrix
     equation
        op(A)*X + ISGN*X*op(B) = scale*C,
     A and B are assumed to be in Schur canonical form, op() represents an
     optional transpose, and ISGN can be -1 or +1.  Scale is an output
     less than or equal to 1, chosen to avoid overflow in X.
     The test code verifies that the following residual does not exceed
     the provided threshold:
        norm(op(A)*X + ISGN*X*op(B) - scale*C) /
            (EPS*max(norm(A),norm(B))*norm(X))
     This routine complements DGET35 by testing with larger,
     random matrices, of which some require rescaling of X to avoid overflow.

Parameters
    THRESH

              THRESH is DOUBLE PRECISION
              A test will count as 'failed' if the residual, computed as
              described above, exceeds THRESH.

    NFAIL

              NFAIL is INTEGER array, dimension (3)
              NFAIL(1) = No. of times residual DTRSYL exceeds threshold THRESH
              NFAIL(2) = No. of times residual DTRSYL3 exceeds threshold THRESH
              NFAIL(3) = No. of times DTRSYL3 and DTRSYL deviate

    RMAX

              RMAX is DOUBLE PRECISION, dimension (2)
              RMAX(1) = Value of the largest test ratio of DTRSYL
              RMAX(2) = Value of the largest test ratio of DTRSYL3

    NINFO

              NINFO is INTEGER array, dimension (2)
              NINFO(1) = No. of times DTRSYL returns an expected INFO
              NINFO(2) = No. of times DTRSYL3 returns an expected INFO

    KNT

              KNT is INTEGER
              Total number of examples tested.

Definition at line 88 of file dsyl01.f.

Author

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