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 generated signals have a unity standard deviation and zero mean value.
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.