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