Changeset 2867

Timestamp:

Nov 12, 2012, 1:40:23 AM (9 years ago)

Author:

Peter

Message:

A log2 function similar to std::log10.

Location:

trunk

Files:

• test/utility.cc (modified) (1 diff)
• yat/utility/utility.h (modified) (3 diffs)

trunk/test/utility.cc

@@ -196 +196 @@
 
   test_compose_functors(suite);
+
+  double x = 8.0;
+  suite.add(suite.equal(utility::log2(x), 3.0));
+  float xf = x;
+  suite.add(suite.equal(utility::log2(xf), 3.0));
+  long double xld = 8.0;
+  suite.add(suite.equal(utility::log2(xld), 3.0));
 
   return suite.return_value();

trunk/yat/utility/utility.h

@@ -1 +1 @@
 #ifndef _theplu_yat_utility_utility_
-#define _theplu_yat_utility_utility_ 
+#define _theplu_yat_utility_utility_
 
 // $Id$
@@ -35 +35 @@
 #include "Exception.h"
 #include "yat_assert.h"
+
+#include <gsl/gsl_math.h>
 
 #include <algorithm>
@@ -194 +196 @@
   template<typename T>
   void load(std::istream& is, std::vector<T>& vec, char sep='\0');
-  
+
+  /**
+     \return base-2 logarithm of x
+
+     \since New in yat 0.10
+   */
+  // c++11 provides std::log2 so perhaps we should call that one if
+  // availalable (but a bit tricky since this is a public header)
+  template<typename T>
+  T log2(T x) { return std::log(x)/M_LN2; }
+
 // private namespace
 namespace detail {