add README

README.md

@@ -0,0 +1,74 @@
+= Introduction =
+
+Calculating Mandelbrot using different ways. It tries to imitate the Mandelbrot
+calculation by Zom-B but be faster in doing so.
+
+This project started by trying to reproduce this zoom sequence but in higher
+resolution:
+
+https://en.wikipedia.org/wiki/File:Mandelbrot_sequence_new.gif
+
+The generator used for this version is available here:
+
+https://github.com/josch/mandelbrot_zomb
+
+= Overview =
+
+mandel:
+	straight forward "long double" based mandelbrot
+	this is obviously the fastest implementation but has limited precision
+mandel_mpfr:
+	mandelbrot using the arbitrary precision mpfr library
+mandel_quad:
+	mandelbrot using gcc libquad
+mandel_dd:
+	mandelbrot using custom double double math
+	this is the fastest implementation given double double precision
+mandel_dd_aa:
+	with antialiasing
+	it is more than three times faster than the Zom-B version (see below)
+
+= How to compile =
+
+Compile by running `make`.
+
+= How to execute =
+
+Each of the tools takes as arguments the width, height, coordinates and
+magnification. Output is in PPM format on standard output.
+
+	$ ./mandel_dd_aa 1920 1080 0.0 0.0 1.0 > out.ppm
+
+You can compress the ppm by using:
+
+	$ convert out.ppm -format png out.png
+
+And even compress it further by doing:
+
+	$ optipng -o4 -i0 out.png
+	$ advpng -z4 out.png
+
+= How to generate zoom animation =
+
+The shell script (with a small python helper) run.sh will generate and execute a
+list of commands to create a zooming sequence of images.
+
+You can create a video of the resulting sequence using:
+
+	$ avconv -i %05d.png out.mp4
+
+= Benchmark =
+
+Benchmark against mandelbrot computation by Zom-B:
+
+at zoom coordinates:
+	x = -0.743643887037158704752191506114774
+	y = 0.131825904205311970493132056385139
+
+1 to 1e32 in 100 steps at 320x240 and no AA took
+	mandel_dd   1:28 h
+        mandel_zomb 2:45 h
+
+1.0e17 at 1920x1080 with 5xAA took
+        mandel_dd_aa 2:38 h
+	mandel_zomb  8:40 h