Fix invalid minimum value for builtin floating types. (ticket #247)

	* mln/value/builtin/floatings.hh: Here.

	* tests/value/builtin/floatings.cc: write test.

milena/ChangeLog

+2011-11-28  Guillaume Lazzara  <z@lrde.epita.fr>
+
+	Fix invalid minimum value for builtin floating types. (ticket #247)
+
+	* mln/value/builtin/floatings.hh: Here.
+
+	* tests/value/builtin/floatings.cc: write test.
+
 2011-11-24  Guillaume Lazzara  <z@lrde.epita.fr>
 	* mln/fun/v2v/rgb_to_hsl.hh: Fix constructor declaration.

milena/mln/value/builtin/floatings.hh

-// Copyright (C) 2007, 2008, 2009 EPITA Research and Development Laboratory (LRDE)
+// Copyright (C) 2007, 2008, 2009, 2011 EPITA Research and Development
+// Laboratory (LRDE)
 //
 // This file is part of Olena.
 //
@@ -75,7 +76,12 @@ namespace mln
 
       static float min()
       {
-	static const float min_ = mln::value::internal::limits<float>::min();
+	// NOTE: limits<float>::min() returns the minimum positive
+	// value. However, in Milena, min() means the minimum value of the
+	// possible range value, i.e., the lowest negative
+	// value. Since float has a symetric range value, we can
+	// safely use -MAX.
+	static const float min_ = - mln::value::internal::limits<float>::max();
 	return min_;
       }
       static float max()
@@ -114,7 +120,12 @@ namespace mln
 
       static double min()
       {
-	static const double min_ = mln::value::internal::limits<double>::min();
+	// NOTE: limits<double>::min() returns the minimum positive
+	// value. However, in Milena, min() means the minimum value of
+	// the possible range value, i.e., the lowest negative
+	// value. Since double has a symetric range value, we can
+	// safely use -MAX.
+	static const double min_ = - mln::value::internal::limits<double>::max();
 	return min_;
       }
       static double max()
@@ -131,7 +142,7 @@ namespace mln
       typedef double                        sum;
 
       static const char* name()
-      { return "float"; }
+      { return "double"; }
 
     };
 

milena/tests/value/builtin/floatings.cc

-// Copyright (C) 2010 EPITA Research and Development Laboratory (LRDE)
+// Copyright (C) 2010, 2011 EPITA Research and Development Laboratory
+// (LRDE)
 //
 // This file is part of Olena.
 //
@@ -28,11 +29,28 @@
 
 int main()
 {
-  std::cout << "mln_sum_product_(float, float)    is `"
-	    << mln_trait_value_name(mln_sum_product_(float, float)) << "'"
-	    << std::endl;
-  // FIXME: Displays `float': probably not good.  :(
-  std::cout << "mln_sum_product_(double, double)) is `"
-	    << mln_trait_value_name(mln_sum_product_(double, double)) << "'"
-	    << std::endl;
+  // Checking sum value type name.
+  mln_assertion(mln_trait_value_name(mln_sum_product_(float, float)) == std::string("float"));
+  mln_assertion(mln_trait_value_name(mln_sum_product_(double, double)) == std::string("double"));
+
+  // Make sure we return the minimum negative value but not the
+  // minimum positive value.
+  mln_assertion(mln_min(float) < 0.);
+  mln_assertion(mln_min(double) < 0.);
+
+  // Make sure the sum value type does not alter precision.
+  {
+    float a = mln_max(float) / 3,
+      b = mln_max(float) / 3;
+    volatile float c = a + b;
+    volatile mln_sum_product_(float, float) d = a + b;
+    mln_assertion(c == d);
+  }
+  {
+    double a = mln_max(double) / 3,
+      b = mln_max(double) / 3;
+    volatile double c = a + b;
+    volatile mln_sum_product_(double, double) d = a + b;
+    mln_assertion(c == d);
+  }
 }