acos-inputs

[Paul Zimmermann]

       Dear Siddhesh,

> If one had to think in an algorithm-agnostic manner, the one factor that 
> typically determines performance of such functions is the precision 
> required to compute an accurate result for a given input.  A set of 
> inputs such that the precision required to compute f(x) is a uniform 
> distribution in the minimum and maximum precision required to compute 
> f(x) may tell us more about the performance of the function.

assume the maximum precision is 10^6 bits, and is needed for only one
input (out of the 2^64 possible for double precision). If you consider
this input, the result of "make bench" will be highly biased, although
in real application this case will never happen.

> Do you think something like this makes sense?  I don't know if 
> performance analysis of libm functions based on precision requirements 
> has been done before, so maybe there is literature out there that may 
> have dealt with this already.

I'm not aware of such literature. Anyway, I will use my own set of inputs
for my application, since the glibc ones give weird results.

Best regards,
Paul