Quad Sieve - Finding B-Smooth Bound

Hi. I'm attempting to implement the quadratic sieve, in part just to improve my own understanding of it. I don't have that strong of a mathematical background either. I understand the basic concept of what's going on, can do the linear algebra steps, but there's one part that many papers seem to either not explain at all or explain with great big fancy mathematical equations that leave me scratching my head. How do choose the value that defines a B-Smooth number? What is the upper bound there?

Thank you!

[jasonp]

This may help.

[science_man_88]

Originally Posted by jasonp

This may help.

wouldn't http://en.wikipedia.org/wiki/Smooth_number also help ?

[bsquared]

Originally Posted by science_man_88

wouldn't http://en.wikipedia.org/wiki/Smooth_number also help ?

That defines smoothness, sure, but it doesn't necessarily help in picking a smoothness bound for the quadratic sieve. The "right" value, as jason's link explains, is dependent on many things (the particular QS implementation, the machine it's running on, other QS parameters, ...) and is usually found through experimentation.