Number of floats between two floats

I don'tknow what you will be using this for - but, if both floats have the same exponent, it should be possible. As the exponent is kept on the high order bits, loading the float bytes (8 bytes in this case) as an integer and subtracting one from another should give the number you want. I use the struct model to pack the floats to a binary representation, and then unpack those as (C, 8 byte) long ints:

>>> import struct
>>> a = struct.pack("dd", 1.000000,1.000001)
>>> b = struct.unpack("ll",a)
>>> b[1] - b[0]
4503599627
>>> a = struct.pack("dd", 1.000000000,1.000000001)
>>> b = struct.unpack("ll",a)
>>> b[1] - b[0]
4503600
>>>