On Tue, Nov 24, 2015 at 12:02:24PM -0500, Ganesh Ajjanagadde wrote: > This rewrites into a similar expression avoiding sqrt. Similarity is > assured since sqrt(x^2 + y^2)/(x+y) lies in [1/sqrt(2), 1] for x, y > 0. > > Tested on x86-64, Haswell, GNU/Linux. > Command: > ffmpeg -f lavfi -i mandelbrot -f null - > > old (draw_mandelbrot): > 277625266 decicycles in draw_mandelbrot, 256 runs, 0 skips > 304527322 decicycles in draw_mandelbrot, 512 runs, 0 skips > 377593582 decicycles in draw_mandelbrot, 1024 runs, 0 skips > 338539499 decicycles in draw_mandelbrot, 2048 runs, 0 skips > 583630357 decicycles in draw_mandelbrot, 4096 runs, 0 skips > > new (draw_mandelbrot): > 274635709 decicycles in draw_mandelbrot, 256 runs, 0 skips > 300287046 decicycles in draw_mandelbrot, 512 runs, 0 skips > 371819935 decicycles in draw_mandelbrot, 1024 runs, 0 skips > 336663765 decicycles in draw_mandelbrot, 2048 runs, 0 skips > 581851016 decicycles in draw_mandelbrot, 4096 runs, 0 skips > > Reviewed-by: Michael Niedermayer <mich...@niedermayer.cc> > Signed-off-by: Ganesh Ajjanagadde <gajjanaga...@gmail.com> > --- > libavfilter/vsrc_mandelbrot.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-)
LGTM thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Rewriting code that is poorly written but fully understood is good. Rewriting code that one doesnt understand is a sign that one is less smart then the original author, trying to rewrite it will not make it better.
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