Re: sanity check - floating point comparison

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 );
}

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 );

 std::deque<double> results;
 // results should have - 1, 3, 4, 0, 5

 for ( int idx ( 0 ) ; idx < jt.size(); ++idx )
 {
   for ( int kdx ( 0 ); kdx < pt.size(); ++kdx )
   {
     if ( isEqual<double>( jt [ idx ], pt [ kdx ] ) )
     {
       results.push_back ( kdx );
     }
   }
 }
 std::copy ( results.begin(), results.end(),
                std::ostream_iterator<int> ( std::cout, "\n" ) );
}

My intent. I'll search the pt container for the values in the jt
container. If found, I'll store - in the result container - the
index/location where the value was found in the pt container. For
example: Search pt container for first element in jt container. So I
found 4 at postions 1, 3 and 4. Similarily for 2. 2 was found within
the pt container at 0 and 5.

Result will print, 1, 3, 4, 0, 5. Works.

What makes me nervous though is the floating point comparsion. After
all numeric_limits is not defined on one platform (using gcc 2.96).

That said, I was opting to use iterators with - I think std::distance

but I'll end up doing floating point comparison anyways, in which case
my own version ( with my own comparator - isEqual) works best. Correct?