Abdelrahman Said
179 lines
4.9 KiB
C
179 lines
4.9 KiB
C
/* -- translated by f2c (version 20240504).
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You must link the resulting object file with libf2c:
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on Microsoft Windows system, link with libf2c.lib;
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on Linux or Unix systems, link with .../path/to/libf2c.a -lm
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or, if you install libf2c.a in a standard place, with -lf2c -lm
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-- in that order, at the end of the command line, as in
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cc *.o -lf2c -lm
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Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
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http://www.netlib.org/f2c/libf2c.zip
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*/
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#include "f2c.h"
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/* Table of constant values */
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static doublereal c_b3 = .66666666666666663;
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/* -----------------------------------------------------------------------
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\BeginDoc
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\Name: dnconv
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\Description:
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Convergence testing for the nonsymmetric Arnoldi eigenvalue routine.
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\Usage:
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call dnconv
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( N, RITZR, RITZI, BOUNDS, TOL, NCONV )
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\Arguments
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N Integer. (INPUT)
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Number of Ritz values to check for convergence.
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RITZR, Double precision arrays of length N. (INPUT)
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RITZI Real and imaginary parts of the Ritz values to be checked
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for convergence.
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BOUNDS Double precision array of length N. (INPUT)
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Ritz estimates for the Ritz values in RITZR and RITZI.
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TOL Double precision scalar. (INPUT)
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Desired backward error for a Ritz value to be considered
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"converged".
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NCONV Integer scalar. (OUTPUT)
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Number of "converged" Ritz values.
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\EndDoc
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-----------------------------------------------------------------------
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\BeginLib
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\Local variables:
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xxxxxx real
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\Routines called:
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arscnd ARPACK utility routine for timing.
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dlamch LAPACK routine that determines machine constants.
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dlapy2 LAPACK routine to compute sqrt(x**2+y**2) carefully.
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\Author
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Danny Sorensen Phuong Vu
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Richard Lehoucq CRPC / Rice University
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Dept. of Computational & Houston, Texas
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Applied Mathematics
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Rice University
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Houston, Texas
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\Revision history:
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xx/xx/92: Version ' 2.1'
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\SCCS Information: @(#)
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FILE: nconv.F SID: 2.3 DATE OF SID: 4/20/96 RELEASE: 2
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\Remarks
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1. xxxx
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\EndLib
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-----------------------------------------------------------------------
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Subroutine */ int igraphdnconv_(integer *n, doublereal *ritzr, doublereal *ritzi,
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doublereal *bounds, doublereal *tol, integer *nconv)
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{
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/* System generated locals */
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integer i__1;
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doublereal d__1, d__2;
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/* Builtin functions */
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double pow_dd(doublereal *, doublereal *);
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/* Local variables */
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integer i__;
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real t0, t1;
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doublereal eps23, temp;
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extern doublereal igraphdlapy2_(doublereal *, doublereal *), igraphdlamch_(char *);
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extern /* Subroutine */ int igrapharscnd_(real *);
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real tnconv=0;
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/* %----------------------------------------------------%
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| Include files for debugging and timing information |
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%----------------------------------------------------%
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%------------------%
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| Scalar Arguments |
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%------------------%
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%-----------------%
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| Array Arguments |
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%-----------------%
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%---------------%
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| Local Scalars |
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%---------------%
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%--------------------%
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| External Functions |
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%--------------------%
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%-----------------------%
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| Executable Statements |
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%-----------------------%
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%-------------------------------------------------------------%
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| Convergence test: unlike in the symmetric code, I am not |
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| using things like refined error bounds and gap condition |
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| because I don't know the exact equivalent concept. |
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| |
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| Instead the i-th Ritz value is considered "converged" when: |
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| bounds(i) .le. ( TOL * | ritz | ) |
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| for some appropriate choice of norm. |
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%-------------------------------------------------------------%
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Parameter adjustments */
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--bounds;
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--ritzi;
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--ritzr;
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/* Function Body */
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igrapharscnd_(&t0);
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/* %---------------------------------%
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| Get machine dependent constant. |
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%---------------------------------% */
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eps23 = igraphdlamch_("Epsilon-Machine");
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eps23 = pow_dd(&eps23, &c_b3);
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*nconv = 0;
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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/* Computing MAX */
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d__1 = eps23, d__2 = igraphdlapy2_(&ritzr[i__], &ritzi[i__]);
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temp = max(d__1,d__2);
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if (bounds[i__] <= *tol * temp) {
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++(*nconv);
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}
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/* L20: */
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}
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igrapharscnd_(&t1);
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tnconv += t1 - t0;
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return 0;
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/* %---------------%
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| End of dnconv |
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%---------------% */
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} /* igraphdnconv_ */
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