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
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
*> \brief \b DSXT1
*
* =========== DOCUMENTATION ===========
*
* Online html documentation available at
* http://www.netlib.org/lapack/explore-html/
*
* Definition:
* ===========
*
* DOUBLE PRECISION FUNCTION DSXT1( IJOB, D1, N1, D2, N2, ABSTOL,
* ULP, UNFL )
*
* .. Scalar Arguments ..
* INTEGER IJOB, N1, N2
* DOUBLE PRECISION ABSTOL, ULP, UNFL
* ..
* .. Array Arguments ..
* DOUBLE PRECISION D1( * ), D2( * )
* ..
*
*
*> \par Purpose:
* =============
*>
*> \verbatim
*>
*> DSXT1 computes the difference between a set of eigenvalues.
*> The result is returned as the function value.
*>
*> IJOB = 1: Computes max { min | D1(i)-D2(j) | }
*> i j
*>
*> IJOB = 2: Computes max { min | D1(i)-D2(j) | /
*> i j
*> ( ABSTOL + |D1(i)|*ULP ) }
*> \endverbatim
*
* Arguments:
* ==========
*
*> \param[in] IJOB
*> \verbatim
*> IJOB is INTEGER
*> Specifies the type of tests to be performed. (See above.)
*> \endverbatim
*>
*> \param[in] D1
*> \verbatim
*> D1 is DOUBLE PRECISION array, dimension (N1)
*> The first array. D1 should be in increasing order, i.e.,
*> D1(j) <= D1(j+1).
*> \endverbatim
*>
*> \param[in] N1
*> \verbatim
*> N1 is INTEGER
*> The length of D1.
*> \endverbatim
*>
*> \param[in] D2
*> \verbatim
*> D2 is DOUBLE PRECISION array, dimension (N2)
*> The second array. D2 should be in increasing order, i.e.,
*> D2(j) <= D2(j+1).
*> \endverbatim
*>
*> \param[in] N2
*> \verbatim
*> N2 is INTEGER
*> The length of D2.
*> \endverbatim
*>
*> \param[in] ABSTOL
*> \verbatim
*> ABSTOL is DOUBLE PRECISION
*> The absolute tolerance, used as a measure of the error.
*> \endverbatim
*>
*> \param[in] ULP
*> \verbatim
*> ULP is DOUBLE PRECISION
*> Machine precision.
*> \endverbatim
*>
*> \param[in] UNFL
*> \verbatim
*> UNFL is DOUBLE PRECISION
*> The smallest positive number whose reciprocal does not
*> overflow.
*> \endverbatim
*
* Authors:
* ========
*
*> \author Univ. of Tennessee
*> \author Univ. of California Berkeley
*> \author Univ. of Colorado Denver
*> \author NAG Ltd.
*
*> \date November 2011
*
*> \ingroup double_eig
*
* =====================================================================
DOUBLE PRECISION FUNCTION DSXT1( IJOB, D1, N1, D2, N2, ABSTOL,
$ ULP, UNFL )
*
* -- LAPACK test routine (version 3.4.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
* November 2011
*
* .. Scalar Arguments ..
INTEGER IJOB, N1, N2
DOUBLE PRECISION ABSTOL, ULP, UNFL
* ..
* .. Array Arguments ..
DOUBLE PRECISION D1( * ), D2( * )
* ..
*
* =====================================================================
*
* .. Parameters ..
DOUBLE PRECISION ZERO
PARAMETER ( ZERO = 0.0D0 )
* ..
* .. Local Scalars ..
INTEGER I, J
DOUBLE PRECISION TEMP1, TEMP2
* ..
* .. Intrinsic Functions ..
INTRINSIC ABS, MAX, MIN
* ..
* .. Executable Statements ..
*
TEMP1 = ZERO
*
J = 1
DO 20 I = 1, N1
10 CONTINUE
IF( D2( J ).LT.D1( I ) .AND. J.LT.N2 ) THEN
J = J + 1
GO TO 10
END IF
IF( J.EQ.1 ) THEN
TEMP2 = ABS( D2( J )-D1( I ) )
IF( IJOB.EQ.2 )
$ TEMP2 = TEMP2 / MAX( UNFL, ABSTOL+ULP*ABS( D1( I ) ) )
ELSE
TEMP2 = MIN( ABS( D2( J )-D1( I ) ),
$ ABS( D1( I )-D2( J-1 ) ) )
IF( IJOB.EQ.2 )
$ TEMP2 = TEMP2 / MAX( UNFL, ABSTOL+ULP*ABS( D1( I ) ) )
END IF
TEMP1 = MAX( TEMP1, TEMP2 )
20 CONTINUE
*
DSXT1 = TEMP1
RETURN
*
* End of DSXT1
*
END
|
