Perturbation formula for burning ship (hopefully correct :P)

[stardust4ever]

Awesome if these advances can be built into the next KF build. Will GPU rendering work well on an Nvidia Gforce 430? 96 Cuda cores. My GPU is pretty old as I never found a need to upgrade it. Will it still outperform my AMD Bulldozer 8150 @4.2Ghz?

[therror]

Yes, I use GeForce 730 (Fermi). It is the same GF108 (96 cores) that GeForce 430. Your results can be similar (IMHO) 

[Kalles Fraktaler]

That is awesome that you are able to generate the abs fractals 3 times faster!
No, I haven't had time to try different conditions in that way

[therror]

Maybe, it works well only in GPUs, because they are sensitive to different if-else conditions int the same warp. Also, GPUs are sensitive to number of variables, because register file is limited and latency of global memory is much more.

[claude]

This is the code in my next version of Kalles Fraktaler (2.12.2, coming soon):

Code:

static inline double d_diffabs(const double c, const double d)
{
  double cd = c + d;
  if (c >= 0.0)
    if (cd >= 0.0)      return d;
    else      return -d - 2.0 * c;
  else
    if (cd > 0.0)      return d + 2.0 * c;
    else      return -d;
}

(and similarly for long double and floatexp)

One test is 7.5% faster than the original code in my fork, with no differences in the image.  A nice improvement, even though not as impressive as the difference on GPU.  Thanks therror!

Note that the "2.0 *" formulation is important, trying to use "cd + c" to save a multiplication leads to unacceptable rounding errors (different images, actually slower due to more references needed, just wrong I guess).