On 10/29/06, Daryle Walker <darylew@hotmail.com> wrote:
Couldn't there be better approximate fractions to use?
I'm not sure if there were other questions implied by the ommited portions of your post, but my best guess is that you are looking for an algorithm which builds a good fit rational number from a float without resorting to a simple and inefficient decimal truncation. If this is what you are looking for then what might work is a function which builds a rational number as a continued fraction. Essentially you strip off the integer part of your rational number, take the inverse of the rest, strip off the integer part, take the inverse, and keep going until you hit a depth you like (3 or 4 is usually plenty). When you hit the maximum depth use zero as an approximation for the fraction built so far and pass it back up. Each level then considers the rational returned to it to be the inverse of part of the fraction it was building, so it flips the numerator and denominator and adds the whole part it stripped off. A greater depth will give you greater accuracy, but you also need to be careful of hitting a depth where extremely small numbers (usually the result of floating point error) will result in overflowing your integer type. Hope this helps -Jason