[Boost-commit] svn:boost r75380 - sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/numeric

Subject: [Boost-commit] svn:boost r75380 - sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/numeric
From: cppljevans_at_[hidden]
Date: 2011-11-07 09:19:35

Author: cppljevans
Date: 2011-11-07 09:19:34 EST (Mon, 07 Nov 2011)
New Revision: 75380
URL: http://svn.boost.org/trac/boost/changeset/75380

Log:
mv'ed function from solve_tridiag.hpp to this file.

Added:
   sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/numeric/almost_equal_relative.hpp   (contents, props changed)

Added: sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/numeric/almost_equal_relative.hpp
==============================================================================
--- (empty file)
+++ sandbox/variadic_templates/sandbox/stepper/boost/array_stepper/numeric/almost_equal_relative.hpp	2011-11-07 09:19:34 EST (Mon, 07 Nov 2011)
@@ -0,0 +1,57 @@
+#ifndef BOOST_ARRAY_STEPPER_NUMERIC_ALMOST_EQUAL_RELATIVE_HPP_INCLUDED
+#define BOOST_ARRAY_STEPPER_NUMERIC_ALMOST_EQUAL_RELATIVE_HPP_INCLUDED
+#include <limits>
+#define TRACE_ALMOST_EQUAL_RELATIVE
+#ifdef TRACE_ALMOST_EQUAL_RELATIVE
+#include <iostream>
+#endif
+namespace boost
+{
+namespace array_stepper
+{
+namespace numeric
+{
+        template
+        < typename Value
+        >
+        bool
+      almost_equal_relative
+        ( Value value_a
+        , Value value_b
+        , Value eps_factor=Value(2.25)
+        )
+       /**@brief
+        *  Are value_a and value_b almost equal?
+        */
+        //Reference:
+        //  http://www.cygnus-software.com/papers/comparingfloats/comparingfloats.htm
+        //
+        {
+            Value max_error=eps_factor*std::numeric_limits<Value>::epsilon();
+            Value abs_diff=std::abs(value_a - value_b);
+            bool abs_lt_max=abs_diff < max_error;
+            if (abs_lt_max)
+                return true;
+            Value abs_a=std::abs(value_a);
+            Value abs_b=std::abs(value_b);
+            Value abs_max=std::max(abs_a,abs_b);
+            Value rel_error=abs_diff / abs_max;
+            bool rel_lt_max=rel_error < max_error;
+            if (rel_lt_max)
+                return true;
+          #ifdef TRACE_ALMOST_EQUAL_RELATIVE
+            std::cout
+              <<"almost_equal_relative:"
+              <<"\n:value_a="<<value_a
+              <<"\n:value_b="<<value_b
+              <<"\n:max_error="<<max_error
+              <<"\n:abs_diff="<<abs_diff
+              <<"\n:rel_error="<<rel_error
+              <<"\n";
+          #endif
+            return false;
+        }
+}//exit numeric namespace
+}//exit array_stepper namespace
+}//exit boost namespace
+#endif