root / bin / compute_areas.cpp @ 1
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| 1 | 1 | akiss | #include <math.h> |
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| 2 | 1 | akiss | #include "constants.h" |
| 3 | 1 | akiss | #include "compute_areas.h" |
| 4 | 1 | akiss | #include <stdio.h> |
| 5 | 1 | akiss | #include <stdlib.h> |
| 6 | 1 | akiss | |
| 7 | 1 | akiss | /* this function computes the areas of the triangles made with two vertices of the same cell and the barycenter of this cell
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| 8 | 1 | akiss | the area is given by half the cross product of the centered coordinates of the vertices */
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| 9 | 1 | akiss | |
| 10 | 1 | akiss | void compute_areas(double *vertices, int *cells_vertices, int *vertices_number_in_each_cell, |
| 11 | 1 | akiss | int cell_number, double *areas){ |
| 12 | 1 | akiss | |
| 13 | 1 | akiss | int i,j,previous;
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| 14 | 1 | akiss | |
| 15 | 1 | akiss | /* usual loop over the cells, then over the vertices of each cell */
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| 16 | 1 | akiss | for (i=0;i<cell_number;i++){ |
| 17 | 1 | akiss | for (j=vertices_number_in_each_cell[i];j<vertices_number_in_each_cell[i+1];j++){ |
| 18 | 1 | akiss | previous=j-1; if (j==vertices_number_in_each_cell[i]){ previous=vertices_number_in_each_cell[i+1]-1;} |
| 19 | 1 | akiss | areas[j]=0.5*(vertices[2*cells_vertices[previous]]*vertices[2*cells_vertices[j]+1]- |
| 20 | 1 | akiss | vertices[2*cells_vertices[previous]+1]*vertices[2*cells_vertices[j]]); |
| 21 | 1 | akiss | } |
| 22 | 1 | akiss | } |
| 23 | 1 | akiss | |
| 24 | 1 | akiss | } |