1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
|
c-----------------------------------------------------------------------
c\BeginDoc
c
c\Name: dnconv
c
c\Description:
c Convergence testing for the nonsymmetric Arnoldi eigenvalue routine.
c
c\Usage:
c call dnconv
c ( N, RITZR, RITZI, BOUNDS, TOL, NCONV )
c
c\Arguments
c N Integer. (INPUT)
c Number of Ritz values to check for convergence.
c
c RITZR, Double precision arrays of length N. (INPUT)
c RITZI Real and imaginary parts of the Ritz values to be checked
c for convergence.
c BOUNDS Double precision array of length N. (INPUT)
c Ritz estimates for the Ritz values in RITZR and RITZI.
c
c TOL Double precision scalar. (INPUT)
c Desired backward error 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\Local variables:
c xxxxxx real
c
c\Routines called:
c arscnd ARPACK utility routine for timing.
c dlamch LAPACK routine that determines machine constants.
c dlapy2 LAPACK routine to compute sqrt(x**2+y**2) carefully.
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\Revision history:
c xx/xx/92: Version ' 2.1'
c
c\SCCS Information: @(#)
c FILE: nconv.F SID: 2.3 DATE OF SID: 4/20/96 RELEASE: 2
c
c\Remarks
c 1. xxxx
c
c\EndLib
c
c-----------------------------------------------------------------------
c
subroutine dnconv (n, ritzr, ritzi, 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
Double precision
& tol
c
c %-----------------%
c | Array Arguments |
c %-----------------%
Double precision
& ritzr(n), ritzi(n), bounds(n)
c
c %---------------%
c | Local Scalars |
c %---------------%
c
integer i
Double precision
& temp, eps23
c
c %--------------------%
c | External Functions |
c %--------------------%
c
Double precision
& dlapy2, dlamch
external dlapy2, dlamch
c %-----------------------%
c | Executable Statements |
c %-----------------------%
c
c %-------------------------------------------------------------%
c | Convergence test: unlike in the symmetric code, I am not |
c | using things like refined error bounds and gap condition |
c | because I don't know the exact equivalent concept. |
c | |
c | Instead the i-th Ritz value is considered "converged" when: |
c | |
c | bounds(i) .le. ( TOL * | ritz | ) |
c | |
c | for some appropriate choice of norm. |
c %-------------------------------------------------------------%
c
call arscnd (t0)
c
c %---------------------------------%
c | Get machine dependent constant. |
c %---------------------------------%
c
eps23 = dlamch('Epsilon-Machine')
eps23 = eps23**(2.0D+0 / 3.0D+0)
c
nconv = 0
do 20 i = 1, n
temp = max( eps23, dlapy2( ritzr(i), ritzi(i) ) )
if (bounds(i) .le. tol*temp) nconv = nconv + 1
20 continue
c
call arscnd (t1)
tnconv = tnconv + (t1 - t0)
c
return
c
c %---------------%
c | End of dnconv |
c %---------------%
c
end
|
