I think the complaint is that presumably, when expanding the float to
double in unpacking, the result is not zero-padded. I cannot reproduce
the problem, though:

py>
hexlify(struct.pack(">d",struct.unpack(">f",struct.pack(">f",1.8183e-7))[0]))
'3e8867a1a0000000'

Seems to me that the zero-padding works just well.

TD22057, why do you say that 1.818300034983622e-07 is not the closest
number. AFAICT, this is not true: this *is* the closest number.