 LAPACK  3.10.0 LAPACK: Linear Algebra PACKage

## ◆ ieeeck()

 integer function ieeeck ( integer ISPEC, real ZERO, real ONE )

IEEECK

Purpose:
``` IEEECK is called from the ILAENV to verify that Infinity and
possibly NaN arithmetic is safe (i.e. will not trap).```
Parameters
 [in] ISPEC ``` ISPEC is INTEGER Specifies whether to test just for inifinity arithmetic or whether to test for infinity and NaN arithmetic. = 0: Verify infinity arithmetic only. = 1: Verify infinity and NaN arithmetic.``` [in] ZERO ``` ZERO is REAL Must contain the value 0.0 This is passed to prevent the compiler from optimizing away this code.``` [in] ONE ``` ONE is REAL Must contain the value 1.0 This is passed to prevent the compiler from optimizing away this code. RETURN VALUE: INTEGER = 0: Arithmetic failed to produce the correct answers = 1: Arithmetic produced the correct answers```

Definition at line 81 of file ieeeck.f.

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
integer function ieeeck(ISPEC, ZERO, ONE)
IEEECK
Definition: ieeeck.f:82
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