Re: sanity check - floating point comparison
Hello,
ma740988 wrote:
template <class T> inline bool isEqual( const T& a, const T& b,
const T epsilon = std::numeric_limits<T>::epsilon() )
{
const T diff = a - b;
return ( diff <= epsilon ) && ( diff >= -epsilon );
}
That epsilon is the difference of 1 and the least value strictly greater
than 1. If you take 1000000 and the least value strictly greater than
1000000, than you will see, that the difference is greater than
epsilon. I don't think you want those values to make isEqual return
false.
int main()
{
std::deque<double> pt ;
pt.push_back ( 2.3123 );
pt.push_back ( 4.3445 );
pt.push_back ( 1.343 );
pt.push_back ( 4.3445 );
pt.push_back ( 4.3445 );
pt.push_back ( 2.3123 );
std::deque<double> jt ;
jt.push_back ( 4.3445 );
jt.push_back ( 2.3123 );
if ( isEqual<double>( jt [ idx ], pt [ kdx ] ) )
my own version ( with my own comparator - isEqual) works best.
Correct?
Almost, just don't abuse epsilon. Your input values seem to be rounded
to 4 digits after decimal point, so take 1e-4 instead of epsilon. You
will have to add epsilon as parameter to isEqual, either as template
argument via some bypass, or in the function argument, or hardcode
epsilon some other way.
Bernd Strieder