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

TESTING/EIG/csyl01.f


subroutine csyl01 (thresh, nfail, rmax, ninfo, knt)
CSYL01

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.

Generated automatically by Doxygen for LAPACK from the source code.

Version 3.12.0 LAPACK