LAPACK 3.11.0 LAPACK: Linear Algebra PACKage
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ieeeck.f
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1*> \brief \b IEEECK
2*
3* =========== DOCUMENTATION ===========
4*
5* Online html documentation available at
6* http://www.netlib.org/lapack/explore-html/
7*
8*> \htmlonly
10*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/ieeeck.f">
11*> [TGZ]</a>
12*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/ieeeck.f">
13*> [ZIP]</a>
14*> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/ieeeck.f">
15*> [TXT]</a>
16*> \endhtmlonly
17*
18* Definition:
19* ===========
20*
21* INTEGER FUNCTION IEEECK( ISPEC, ZERO, ONE )
22*
23* .. Scalar Arguments ..
24* INTEGER ISPEC
25* REAL ONE, ZERO
26* ..
27*
28*
29*> \par Purpose:
30* =============
31*>
32*> \verbatim
33*>
34*> IEEECK is called from the ILAENV to verify that Infinity and
35*> possibly NaN arithmetic is safe (i.e. will not trap).
36*> \endverbatim
37*
38* Arguments:
39* ==========
40*
41*> \param[in] ISPEC
42*> \verbatim
43*> ISPEC is INTEGER
44*> Specifies whether to test just for infinity arithmetic
45*> or whether to test for infinity and NaN arithmetic.
46*> = 0: Verify infinity arithmetic only.
47*> = 1: Verify infinity and NaN arithmetic.
48*> \endverbatim
49*>
50*> \param[in] ZERO
51*> \verbatim
52*> ZERO is REAL
53*> Must contain the value 0.0
54*> This is passed to prevent the compiler from optimizing
55*> away this code.
56*> \endverbatim
57*>
58*> \param[in] ONE
59*> \verbatim
60*> ONE is REAL
61*> Must contain the value 1.0
62*> This is passed to prevent the compiler from optimizing
63*> away this code.
64*>
65*> RETURN VALUE: INTEGER
66*> = 0: Arithmetic failed to produce the correct answers
67*> = 1: Arithmetic produced the correct answers
68*> \endverbatim
69*
70* Authors:
71* ========
72*
73*> \author Univ. of Tennessee
74*> \author Univ. of California Berkeley
75*> \author Univ. of Colorado Denver
76*> \author NAG Ltd.
77*
78*> \ingroup OTHERauxiliary
79*
80* =====================================================================
81 INTEGER FUNCTION ieeeck( ISPEC, ZERO, ONE )
82*
83* -- LAPACK auxiliary routine --
84* -- LAPACK is a software package provided by Univ. of Tennessee, --
85* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
86*
87* .. Scalar Arguments ..
88 INTEGER ispec
89 REAL one, zero
90* ..
91*
92* =====================================================================
93*
94* .. Local Scalars ..
95 REAL nan1, nan2, nan3, nan4, nan5, nan6, neginf,
96 \$ negzro, newzro, posinf
97* ..
98* .. Executable Statements ..
99 ieeeck = 1
100*
101 posinf = one / zero
102 IF( posinf.LE.one ) THEN
103 ieeeck = 0
104 RETURN
105 END IF
106*
107 neginf = -one / zero
108 IF( neginf.GE.zero ) THEN
109 ieeeck = 0
110 RETURN
111 END IF
112*
113 negzro = one / ( neginf+one )
114 IF( negzro.NE.zero ) THEN
115 ieeeck = 0
116 RETURN
117 END IF
118*
119 neginf = one / negzro
120 IF( neginf.GE.zero ) THEN
121 ieeeck = 0
122 RETURN
123 END IF
124*
125 newzro = negzro + zero
126 IF( newzro.NE.zero ) THEN
127 ieeeck = 0
128 RETURN
129 END IF
130*
131 posinf = one / newzro
132 IF( posinf.LE.one ) THEN
133 ieeeck = 0
134 RETURN
135 END IF
136*
137 neginf = neginf*posinf
138 IF( neginf.GE.zero ) THEN
139 ieeeck = 0
140 RETURN
141 END IF
142*
143 posinf = posinf*posinf
144 IF( posinf.LE.one ) THEN
145 ieeeck = 0
146 RETURN
147 END IF
148*
149*
150*
151*
152* Return if we were only asked to check infinity arithmetic
153*
154 IF( ispec.EQ.0 )
155 \$ RETURN
156*
157 nan1 = posinf + neginf
158*
159 nan2 = posinf / neginf
160*
161 nan3 = posinf / posinf
162*
163 nan4 = posinf*zero
164*
165 nan5 = neginf*negzro
166*
167 nan6 = nan5*zero
168*
169 IF( nan1.EQ.nan1 ) THEN
170 ieeeck = 0
171 RETURN
172 END IF
173*
174 IF( nan2.EQ.nan2 ) THEN
175 ieeeck = 0
176 RETURN
177 END IF
178*
179 IF( nan3.EQ.nan3 ) THEN
180 ieeeck = 0
181 RETURN
182 END IF
183*
184 IF( nan4.EQ.nan4 ) THEN
185 ieeeck = 0
186 RETURN
187 END IF
188*
189 IF( nan5.EQ.nan5 ) THEN
190 ieeeck = 0
191 RETURN
192 END IF
193*
194 IF( nan6.EQ.nan6 ) THEN
195 ieeeck = 0
196 RETURN
197 END IF
198*
199 RETURN
200 END
integer function ieeeck(ISPEC, ZERO, ONE)
IEEECK
Definition: ieeeck.f:82