Tricky. How accurate does it need to be?
Why 0.728? Where does this question come from?
Also, what is the possible range of y?
It can be solved if you can use 44 bit arithmetic or more: multiply by 0x02E978D5 and shift the result right by 26 bits, which is accurate to at least 4 decimal places (checked on a spreadsheet) but needs that extra headroom.
Last edited by xpi0t0s; 25Oct2011 at 22:36..