Function to_float 

pub fn to_float(bits: UInt, size: i32, m: i32, n: i32) -> Result<f64, String>

Compute the real value represented by bits.

use fixed2float::to_float;
assert_eq!(to_float(0b0_000100110000_00100001, 21, 12, 8), Ok(304.12890625));