random number

--------- Possion disk sampling.

--------- Perlin Noise

http://devmag.org.za/2009/05/03/poisson-disk-sampling/

http://devmag.org.za/2009/04/25/perlin-noise/

http://devmag.org.za/2011/06/25/implementing-and-debugging-the-perlin-noise-algorithm/

Bezier curves

http://devmag.org.za/2011/04/05/bzier-curves-a-tutorial/

http://devmag.org.za/2011/06/23/bzier-path-algorithms/

近来遇到的问题是怎么求underdetermined systems, 以及minimize a quadratic energy, 我还是好像system of equation 跟 optimization是怎么联系在一起的.