FloatingPointComparisson.hpp

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#ifndef FLOATINGPOINTCOMPARISSON_HPP_
#define FLOATINGPOINTCOMPARISSON_HPP_

#include <limits>

namespace Numerics {


                         inline double AbsoluteValue( double a )
                         {
                                 return( ( ( a < static_cast< double >( 0 ) )? -a : a ) );
                         }

                                 inline double ___safe_fpt_division( const double f1, const double f2 )
                                 {
                                        #ifdef ASSERT_ON
                                         assert( f1 >= static_cast< double >( 0 ) );
                                         assert( f2 >= static_cast< double >( 0 ) );
                                        #endif

                                         /* Avoid overflow */
                                         if( f2 < static_cast< double >( 1 ) && f1 > f2*std::numeric_limits< double >::max( ) )
                                                 return std::numeric_limits<double>::max( );


                                         /* Avoid underflow */
                                         if( f1 == static_cast< double >( 0 ) ||
                                         f2 > static_cast< double >( 1 ) && f1 < f2*std::numeric_limits< double >::min( ) )
                                                 return static_cast< double >( 0 );

                                         return( f1/f2 );
                                 }

                                 inline bool fpointequals( const double a, const double b, double TOL=1e-9 )
                                 {
                                         double diff      = a-b;
                                         double adiff     = AbsoluteValue( diff );
                                         double d1                = ___safe_fpt_division( adiff, AbsoluteValue( a ) );
                                         double d2                = ___safe_fpt_division( adiff, AbsoluteValue( b ) );
                                         bool predicate1  = (d1 <= TOL);
                                         bool predicate2  = (d2 <= TOL);

                                         if( (predicate1 || predicate2) )
                                                 return true;
                                         return false;
                                 }


}
#endif /* FLOATINGPOINTCOMPARISSON_HPP_ */