23 August 2004 09:29:41 AM CVT_DATASET (C++ version) Generate a CVT dataset. Compiled on Aug 23 2004 at 08:56:51 This program is meant to be used interactively. It is also possible to prepare a simple input file beforehand and use it in batch mode. The program requests input values from the user: * NDIM, the spatial dimension, * N, the number of points to generate, * SEED, a seed to use for random number generation, * INIT, initialize the points: ** file, read data from a file; ** GRID, by picking points from a grid; ** HALTON, from a Halton sequence; ** RANDOM, using FORTRAN RANDOM function; ** UNIFORM, using a simple uniform RNG; * IT_MAX, the maximum number of iterations. * IT_TOL, the iteration tolerance. * SAMPLE, how to conduct the sampling. ** GRID, by picking points from a grid; ** HALTON, from a Halton sequence; ** RANDOM, using FORTRAN RANDOM function; ** UNIFORM, using a simple uniform RNG; * SAMPLE_NUM, the number of sample points. * BATCH, the number of sample points to generate at one time. The program generates the data, writes it to the file cvt_NDIM_N.txt where "NDIM" and "N" are the numeric values specified by the user, and then asks the user for more input. To indicate that no further computations are desired, it is enough to input a nonsensical value, such as -1. * * * Ready to generate a new dataset: * * Enter NDIM, the spatial dimension: (0 or any negative value terminates execution). User input NDIM = 2 Enter N, the number of points to generate: (0 or any negative value terminates execution). User input N = 85 Enter SEED, a seed for the random number generator: (Any negative value terminates execution). User input SEED = 123456789 INIT is the method of initializing the data: file read data from a file; GRID by picking points from a grid; HALTON from a Halton sequence; RANDOM using C++ RANDOM function; UNIFORM using a simple uniform RNG; (A blank value terminates execution). Enter INIT: User input INIT = "uniform". IT_MAX is the maximum number of iterations. An iteration carries out the following steps: * the Voronoi region associated with each generator is estimated by sampling; * the centroid of each Voronoi region is estimated. * the generator is replaced by the centroid. If "enough" sampling points are used, and "enough" iterations are taken, this process will converge. (A negative value terminates execution). Enter IT_MAX: User input IT_MAX = 40 IT_TOL is the iteration tolerance. Each iteration replaces the generators by the centroids. The L2 norm of the difference between these two sets of points is an indirect measure of convergence. If this L2 norm falls below IT_TOL, the iteration is presumed to have converged, and is terminated early. A zero value is acceptable, and simply means that early termination will not occur. (A negative value terminates execution). Enter IT_TOL: User input IT_TOL = 0 SAMPLE is the method of sampling the region: GRID by picking points from a grid; HALTON from a Halton sequence; RANDOM using C++ RANDOM function; UNIFORM using a simple uniform RNG; (A blank value terminates execution). Enter SAMPLE: User input SAMPLE = "random". SAMPLE_NUM is the number of sample points. The Voronoi regions will be explored by generating SAMPLE_NUM points. For each sample point, the nearest generator is found. Using more points gives a better estimate of these regions. SAMPLE_NUM should be much larger than N, the number of generators. (A zero or negative value terminates execution.) Enter SAMPLE_NUM: User input SAMPLE_NUM = 10000 BATCH is the number of sample points to create at one time. BATCH should be between 1 and SAMPLE_NUM. It is FASTER to set BATCH to SAMPLE_NUM; setting BATCH to 1 requires the least memory. (A zero or negative value terminates execution.) Enter BATCH: User input BATCH = 1000 Step L2-Change 1 2.63286 2 1.14514 3 0.793076 4 0.606064 5 0.552946 6 0.498189 7 0.434172 8 0.425586 9 0.434282 10 0.401204 11 0.38292 12 0.400471 13 0.398572 14 0.393948 15 0.355339 16 0.383308 17 0.361551 18 0.388119 19 0.399997 20 0.377229 21 0.371202 22 0.35273 23 0.35106 24 0.353626 25 0.323028 26 0.352364 27 0.334663 28 0.350886 29 0.399521 30 0.38168 31 0.397101 32 0.346694 33 0.352239 34 0.350715 35 0.394064 36 0.394464 37 0.407328 38 0.37926 39 0.349724 40 0.370083 The data was written to the file "cvt_2_85.txt * * * Ready to generate a new dataset: * * Enter NDIM, the spatial dimension: (0 or any negative value terminates execution). User input NDIM = -1 CVT_DATASET The input value of NDIM = -1 is interpreted as a request for termination. Normal end of execution. 23 August 2004 09:29:43 AM