TESTING/EIG/csyl01.f(3)    Library Functions Manual    TESTING/EIG/csyl01.f(3)

NAME
       TESTING/EIG/csyl01.f

SYNOPSIS
   Functions/Subroutines
       subroutine csyl01 (thresh, nfail, rmax, ninfo, knt)
           CSYL01

Function/Subroutine Documentation
   subroutine csyl01 (real thresh, integer, dimension( 3 ) nfail, real,
       dimension( 2 ) rmax, integer, dimension( 2 ) ninfo, integer knt)
       CSYL01

       Purpose:


            CSYL01 tests CTRSYL and CTRSYL3, routines for solving the Sylvester matrix
            equation

               op(A)*X + ISGN*X*op(B) = scale*C,

            where op(A) and op(B) are both upper triangular form, op() represents an
            optional conjugate 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 CGET35 by testing with larger,
            random matrices, of which some require rescaling of X to avoid overflow.

       Parameters
           THRESH

                     THRESH is REAL
                     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 CTRSYL exceeds threshold THRESH
                     NFAIL(2) = No. of times residual CTRSYL3 exceeds threshold THRESH
                     NFAIL(3) = No. of times CTRSYL3 and CTRSYL deviate

           RMAX

                     RMAX is DOUBLE PRECISION array, dimension (2)
                     RMAX(1) = Value of the largest test ratio of CTRSYL
                     RMAX(2) = Value of the largest test ratio of CTRSYL3

           NINFO

                     NINFO is INTEGER array, dimension (2)
                     NINFO(1) = No. of times CTRSYL where INFO is nonzero
                     NINFO(2) = No. of times CTRSYL3 where INFO is nonzero

           KNT

                     KNT is INTEGER
                     Total number of examples tested.

       Definition at line 88 of file csyl01.f.

Author
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LAPACK                          Version 3.12.0         TESTING/EIG/csyl01.f(3)