The present submission is a set of four Matlab functions that provides a generation of:
1) Pink (flicker) noise - power spectral density -3 dB/oct
2) Red (brown(ian)) noise - power spectral density -6 dB/oct
3) Blue noise - power spectral density +3 dB/oct
4) Violet (purple) noise - power spectral density +6 dB/oct
A brief example is given to clarify the usage of the functions. The input and output arguments are given in the beginning of each function.
The code is based on the theory described in:
 D. Manolakis, V. Ingle. Applied Digital Signal Processing. Cambridge, Cambridge University Press, 2011.
 T. Dutoit, F. Marques. Applied Signal Processing - A MATLAB-Based Proof of Concept. New York, Springer, 2009.
 J. Kasdin. “Discrete Simulation of Colored Noise and Stochastic Processes and 1/f^a Power Law Noise Generation”. Proceedings of the IEEE, Volume 83, Number 5, 1995, pages 802-827.