|Re: [hatari-devel] DSP Mandelbrot bug|
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|Douglas and Laurent, i'm very sorry! Obviously the hint to test on real hardware was the solution ....|
douglas, I like the optimizations, although i don't understand them ;-)
I hope you did not invest too much time trying to find that none existing bug (i did).
You might like the explanation from a NeXT insider:
"The generation of "Mandelbrot" figures is floating point intensive. In particular, the fine details that appear in the renderings are closely related to the maximum precision of the floating point calculations as the function is iterated many, many times.
The FPU has 80 bit registers (64 bit mantissa, sign bit, and 15 bit signed exponent)
The 56K DSP is a fixed point processor with 24 bit data words and registers that can be ganged for a 48 bit word, and 56 bit accumulators.
The different levels of precision produce different results when used to solve heavily iterative math. That shows up in the displayed results. (And yes, Prof. Crandall had to explain this to Mr. Jobs...)"
Am 23.11.2015 um 11:37 schrieb Douglas Little <doug694@xxxxxxxxxxxxxx>:
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