| re: float/double
float is normally called single precision and double is double precision.
On most common implementations a float is 32 bits (4 bytes) and a double is 64 bits (8 bytes). Because of this increase in memory usage a double can (normally) hold 15 significant digits where as a float holds 7. A Double can also hold a much much larger range of numbers than a float.
With today's computers with excess memory the normal rule of thumb is to use the double type unless you have a communicatable reason why you need to use floats.
| 
