This set of m-files demonstrates the main results in [1]. "demo.m" runs the kernel k-means Nystrom approximation. To run this demo, simply start Matlab and run the demo file. Acknowledgment: The work described in the code was published in: [1] Li He and Hong Zhang. Kernel K-means Sampling for Nystrom Approximation. IEEE Transactions on Image Processing, Volume 27, Issue 5, May 2018, pp. 2108-2120.