[Open-graphics] Other interesting bits of math to do in FPGAs

[Farhan Mohamed Ali]

On Wed, September 19, 2007 9:20 am, Timothy Normand Miller said:
> We've talked a lot about multipliers recently, and in the past, we've 
> talked about floating point adders, multipliers, and reciprocal.
> 
Is there any RTL for that stuff? I can't seem to find it on the 
repository. If there is more work needed here i will be more than happy 
to do it, i like this stuff.

> Another interesting function that might be good to implement is the 
> logarithm.  In fact, I think we may actually need that to do MIP-mapped
> textures.
> 
> But there are more general applications.  I've studied various problems
> in AI where numberous probabilities must be multiplied together, for
> instance in hidden markov models. (HMMs).  To avoid having to multiply
> smaller and smaller numbers, people commonly switch to log space.
> Instead of multiplying small positive numbers, you add large negative
> numbers.  Logs of probabilities are commonly referred to as "likelihoods"
> or "log likelihoods."  I don't remember enough about the math to explain
> the advantage, but apparently, there is one. < and > retain the same
> relative meaning, and there's often no point in switching back to
> probability space, because often you just want to compare.
> 
> Depending on what sorts of applications we want to implement besides 
> graphics, we may need a library of things like this.  For instance, we 
> could so automatic speech recognition in hardware, which is typically 
> implemented using HMMs.
> 
What kind of log function are you thinking about? Just an integer log?