/* -- translated by f2c (version 20100827).
You must link the resulting object file with libf2c:
on Microsoft Windows system, link with libf2c.lib;
on Linux or Unix systems, link with .../path/to/libf2c.a -lm
or, if you install libf2c.a in a standard place, with -lf2c -lm
-- in that order, at the end of the command line, as in
cc *.o -lf2c -lm
Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
http://www.netlib.org/f2c/libf2c.zip
*/
#include "f2c.h"
/* Table of constant values */
static doublereal c_b3 = .66666666666666663;
/* -----------------------------------------------------------------------
\BeginDoc
\Name: dnconv
\Description:
Convergence testing for the nonsymmetric Arnoldi eigenvalue routine.
\Usage:
call dnconv
( N, RITZR, RITZI, BOUNDS, TOL, NCONV )
\Arguments
N Integer. (INPUT)
Number of Ritz values to check for convergence.
RITZR, Double precision arrays of length N. (INPUT)
RITZI Real and imaginary parts of the Ritz values to be checked
for convergence.
BOUNDS Double precision array of length N. (INPUT)
Ritz estimates for the Ritz values in RITZR and RITZI.
TOL Double precision scalar. (INPUT)
Desired backward error for a Ritz value to be considered
"converged".
NCONV Integer scalar. (OUTPUT)
Number of "converged" Ritz values.
\EndDoc
-----------------------------------------------------------------------
\BeginLib
\Local variables:
xxxxxx real
\Routines called:
second ARPACK utility routine for timing.
dlamch LAPACK routine that determines machine constants.
dlapy2 LAPACK routine to compute sqrt(x**2+y**2) carefully.
\Author
Danny Sorensen Phuong Vu
Richard Lehoucq CRPC / Rice University
Dept. of Computational & Houston, Texas
Applied Mathematics
Rice University
Houston, Texas
\Revision history:
xx/xx/92: Version ' 2.1'
\SCCS Information: @(#)
FILE: nconv.F SID: 2.3 DATE OF SID: 4/20/96 RELEASE: 2
\Remarks
1. xxxx
\EndLib
-----------------------------------------------------------------------
Subroutine */ int igraphdnconv_(integer *n, doublereal *ritzr, doublereal *ritzi,
doublereal *bounds, doublereal *tol, integer *nconv)
{
/* System generated locals */
integer i__1;
doublereal d__1, d__2;
/* Builtin functions */
double pow_dd(doublereal *, doublereal *);
/* Local variables */
integer i__;
real t0, t1;
doublereal eps23, temp;
extern doublereal igraphdlapy2_(doublereal *, doublereal *), igraphdlamch_(char *);
extern /* Subroutine */ int igraphsecond_(real *);
real tnconv = 0.;
/* %----------------------------------------------------%
| Include files for debugging and timing information |
%----------------------------------------------------%
%------------------%
| Scalar Arguments |
%------------------%
%-----------------%
| Array Arguments |
%-----------------%
%---------------%
| Local Scalars |
%---------------%
%--------------------%
| External Functions |
%--------------------%
%-----------------------%
| Executable Statements |
%-----------------------%
%-------------------------------------------------------------%
| Convergence test: unlike in the symmetric code, I am not |
| using things like refined error bounds and gap condition |
| because I don't know the exact equivalent concept. |
| |
| Instead the i-th Ritz value is considered "converged" when: |
| |
| bounds(i) .le. ( TOL * | ritz | ) |
| |
| for some appropriate choice of norm. |
%-------------------------------------------------------------%
Parameter adjustments */
--bounds;
--ritzi;
--ritzr;
/* Function Body */
igraphsecond_(&t0);
/* %---------------------------------%
| Get machine dependent constant. |
%---------------------------------% */
eps23 = igraphdlamch_("Epsilon-Machine");
eps23 = pow_dd(&eps23, &c_b3);
*nconv = 0;
i__1 = *n;
for (i__ = 1; i__ <= i__1; ++i__) {
/* Computing MAX */
d__1 = eps23, d__2 = igraphdlapy2_(&ritzr[i__], &ritzi[i__]);
temp = max(d__1,d__2);
if (bounds[i__] <= *tol * temp) {
++(*nconv);
}
/* L20: */
}
igraphsecond_(&t1);
tnconv += t1 - t0;
return 0;
/* %---------------%
| End of dnconv |
%---------------% */
} /* igraphdnconv_ */