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comparison liboctave/lo-mappers.cc @ 7740:39930366b709

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implement builtin log2
author Jaroslav Hajek <highegg@gmail.com>
date Wed, 30 Apr 2008 03:30:34 -0400
parents 446dec9d1de5
children 82be108cc558
comparison
equal deleted inserted replaced
7739:ca9bfe159144 7740:39930366b709
137 return log2 (x); 137 return log2 (x);
138 #else 138 #else
139 #if defined (M_LN2) 139 #if defined (M_LN2)
140 static double ln2 = M_LN2; 140 static double ln2 = M_LN2;
141 #else 141 #else
142 static double ln2 = log2 (2); 142 static double ln2 = log (2);
143 #endif 143 #endif
144 144
145 return log (x) / ln2; 145 return log (x) / ln2;
146 #endif 146 #endif
147 }
148
149 Complex
150 xlog2 (const Complex& x)
151 {
152 #if defined (M_LN2)
153 static double ln2 = M_LN2;
154 #else
155 static double ln2 = log (2);
156 #endif
157
158 return std::log (x) / ln2;
147 } 159 }
148 160
149 double 161 double
150 xexp2 (double x) 162 xexp2 (double x)
151 { 163 {
153 return exp2 (x); 165 return exp2 (x);
154 #else 166 #else
155 #if defined (M_LN2) 167 #if defined (M_LN2)
156 static double ln2 = M_LN2; 168 static double ln2 = M_LN2;
157 #else 169 #else
158 static double ln2 = log2 (2); 170 static double ln2 = log (2);
159 #endif 171 #endif
160 172
161 return exp (x * ln2); 173 return exp (x * ln2);
162 #endif 174 #endif
175 }
176
177 double
178 xlog2 (double x, int& exp)
179 {
180 return frexp (x, &exp);
181 }
182
183 Complex
184 xlog2 (const Complex& x, int& exp)
185 {
186 double ax = std::abs (x);
187 double lax = xlog2 (ax, exp);
188 return (exp == 0) ? x : (x / ax) * lax;
163 } 189 }
164 190
165 // double -> bool mappers. 191 // double -> bool mappers.
166 192
167 bool 193 bool