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c-----------------------------------------------------------------------
c\BeginDoc
c
c\Name: ssconv
c
c\Description:
c Convergence testing for the symmetric Arnoldi eigenvalue routine.
c
c\Usage:
c call ssconv
c ( N, RITZ, BOUNDS, TOL, NCONV )
c
c\Arguments
c N Integer. (INPUT)
c Number of Ritz values to check for convergence.
c
c RITZ Real array of length N. (INPUT)
c The Ritz values to be checked for convergence.
c
c BOUNDS Real array of length N. (INPUT)
c Ritz estimates associated with the Ritz values in RITZ.
c
c TOL Real scalar. (INPUT)
c Desired relative accuracy for a Ritz value to be considered
c "converged".
c
c NCONV Integer scalar. (OUTPUT)
c Number of "converged" Ritz values.
c
c\EndDoc
c
c-----------------------------------------------------------------------
c
c\BeginLib
c
c\Routines called:
c arscnd ARPACK utility routine for timing.
c slamch LAPACK routine that determines machine constants.
c
c\Author
c Danny Sorensen Phuong Vu
c Richard Lehoucq CRPC / Rice University
c Dept. of Computational & Houston, Texas
c Applied Mathematics
c Rice University
c Houston, Texas
c
c\SCCS Information: @(#)
c FILE: sconv.F SID: 2.4 DATE OF SID: 4/19/96 RELEASE: 2
c
c\Remarks
c 1. Starting with version 2.4, this routine no longer uses the
c Parlett strategy using the gap conditions.
c
c\EndLib
c
c-----------------------------------------------------------------------
c
subroutine ssconv (n, ritz, bounds, tol, nconv)
c
c %----------------------------------------------------%
c | Include files for debugging and timing information |
c %----------------------------------------------------%
c
include 'debug.h'
include 'stat.h'
c
c %------------------%
c | Scalar Arguments |
c %------------------%
c
integer n, nconv
Real
& tol
c
c %-----------------%
c | Array Arguments |
c %-----------------%
c
Real
& ritz(n), bounds(n)
c
c %---------------%
c | Local Scalars |
c %---------------%
c
integer i
Real
& temp, eps23
c
c %-------------------%
c | External routines |
c %-------------------%
c
Real
& slamch
external slamch
c %---------------------%
c | Intrinsic Functions |
c %---------------------%
c
intrinsic abs
c
c %-----------------------%
c | Executable Statements |
c %-----------------------%
c
call arscnd (t0)
c
eps23 = slamch('Epsilon-Machine')
eps23 = eps23**(2.0E+0 / 3.0E+0)
c
nconv = 0
do 10 i = 1, n
c
c %-----------------------------------------------------%
c | The i-th Ritz value is considered "converged" |
c | when: bounds(i) .le. TOL*max(eps23, abs(ritz(i))) |
c %-----------------------------------------------------%
c
temp = max( eps23, abs(ritz(i)) )
if ( bounds(i) .le. tol*temp ) then
nconv = nconv + 1
end if
c
10 continue
c
call arscnd (t1)
tsconv = tsconv + (t1 - t0)
c
return
c
c %---------------%
c | End of ssconv |
c %---------------%
c
end
|
