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116 lines
3.9 KiB
116 lines
3.9 KiB
/*
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* Copyright(C) 1999-2020, 2022, 2023 National Technology & Engineering Solutions
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* of Sandia, LLC (NTESS). Under the terms of Contract DE-NA0003525 with
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* NTESS, the U.S. Government retains certain rights in this software.
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*
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* See packages/seacas/LICENSE for details
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*/
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#include "defs.h" // for TRUE
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#include "smalloc.h" // for sfree, smalloc
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#include "structs.h" // for vtx_data
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#include <stdio.h> // for printf
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void inertial2d(struct vtx_data **graph, /* graph data structure for weights */
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int nvtxs, /* number of vtxs in graph */
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int cube_or_mesh, /* 0 => hypercube, d => d-dimensional mesh */
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int nsets, /* number of sets to divide into */
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float *x, float *y, /* x and y coordinates of vertices */
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int *sets, /* set each vertex gets assigned to */
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double *goal, /* desired set sizes */
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int using_vwgts /* are vertex weights being used? */
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)
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{
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extern int DEBUG_INERTIAL; /* debug flag for inertial method */
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extern double inertial_axis_time; /* time spent finding inertial axis */
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extern double median_time; /* time spent computing medians */
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double tensor[2][2]; /* inertial tensor */
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double evec[2]; /* eigenvector of tensor */
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double *value; /* values along selected direction to sort */
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double xcm, ycm; /* center of mass in each direction */
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double xx, yy, xy; /* elements of inertial tensor */
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double xdif, ydif; /* deviation from center of mass */
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double eval, res; /* eigenvalue and error in eval calculation */
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double vwgt_sum; /* sum of all the vertex weights */
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double time; /* timing parameters */
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int *space; /* space required by median routine */
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int i; /* loop counter */
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double seconds(void);
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/* Compute center of mass and total mass. */
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time = seconds();
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xcm = ycm = 0.0;
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if (using_vwgts) {
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vwgt_sum = 0.0;
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for (i = 1; i <= nvtxs; i++) {
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vwgt_sum += graph[i]->vwgt;
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xcm += graph[i]->vwgt * x[i];
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ycm += graph[i]->vwgt * y[i];
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}
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}
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else {
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vwgt_sum = nvtxs;
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for (i = 1; i <= nvtxs; i++) {
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xcm += x[i];
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ycm += y[i];
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}
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}
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xcm /= vwgt_sum;
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ycm /= vwgt_sum;
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/* Generate 3 elements of Inertial tensor. */
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xx = yy = xy = 0.0;
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if (using_vwgts) {
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for (i = 1; i <= nvtxs; i++) {
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xdif = x[i] - xcm;
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ydif = y[i] - ycm;
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xx += graph[i]->vwgt * xdif * xdif;
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yy += graph[i]->vwgt * ydif * ydif;
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xy += graph[i]->vwgt * xdif * ydif;
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}
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}
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else {
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for (i = 1; i <= nvtxs; i++) {
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xdif = x[i] - xcm;
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ydif = y[i] - ycm;
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xx += xdif * xdif;
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yy += ydif * ydif;
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xy += xdif * ydif;
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}
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}
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/* Compute eigenvector with maximum eigenvalue. */
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tensor[0][0] = xx;
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tensor[1][1] = yy;
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tensor[1][0] = tensor[0][1] = xy;
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evals2(tensor, &res, &eval);
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eigenvec2(tensor, eval, evec, &res);
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inertial_axis_time += seconds() - time;
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if (DEBUG_INERTIAL > 0) {
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printf("Principle Axis = (%g, %g), Eval=%g, Residual=%e\n", evec[0], evec[1], eval, res);
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}
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/* Allocate space for value array. */
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value = smalloc((nvtxs + 1) * sizeof(double));
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/* Calculate value to sort/split on for each cell. */
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/* This is inner product with eigenvector. */
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for (i = 1; i <= nvtxs; i++) {
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value[i] = (x[i] - xcm) * evec[0] + (y[i] - ycm) * evec[1];
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}
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/* Now find the median value and partition based upon it. */
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space = smalloc(nvtxs * sizeof(int));
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time = seconds();
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rec_median_1(graph, value, nvtxs, space, cube_or_mesh, nsets, goal, using_vwgts, sets, TRUE);
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median_time += seconds() - time;
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sfree(space);
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sfree(value);
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}
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