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