natgrid_nonlinear.rar_网格插值

#include <stdio.h> /* Function prototype for c_natgrids */ extern float *c_natgrids(int, float [], float [], float [], int, int, float [], float [], int *); /* Specify number of input data points and the size of the output grid */ #define NUMIN 80732 #define NUMXOUT 600 #define NUMYOUT 200 /* Specify the range of the input, or type NULL to have the program calculate it */ #define XMAX 167 #define XMIN 161 #define YMAX 74 #define YMIN 72 main(int argc, char *argv[]) { FILE *in; int i, j, k, ier, count=0, nitems, temp; float *out, xo[NUMXOUT], yo[NUMYOUT], xc, yc; float x[NUMIN], y[NUMIN], z[NUMIN]; float x_max, x_min, y_max, y_min; /* Check if the file argument is present */ if (!argv[1]) { printf( "\nNo input file specified\n" ); exit(0); } /* Check if the file exists */ in=fopen(argv[1],"r"); if (in == NULL) { printf( "\nUnable to open file\n" ); exit(0); } /* Read in longitude, latitude, and elevation from file */ while(1) { nitems = fscanf(in, "%f\t%f\t%f\n", &x[count], &y[count], &z[count]); if (nitems == EOF) break; count++; } /* Find the x and y range of input */ if ((XMAX == NULL) || (XMIN == NULL) || (YMAX == NULL) || (YMIN == NULL)) { x_max = x[0]; x_min = x[0]; y_max = y[0]; y_min = y[0]; for (temp=0; temp < count; temp++) { if (x[temp] > x_max) { x_max = x[temp]; } if (x[temp] < x_min) { x_min = x[temp]; } if (y[temp] > y_max) { y_max = y[temp]; } if (y[temp] < y_min) { y_min = y[temp]; } } } if (XMAX != NULL) { x_max = XMAX; } if (XMIN != NULL) { x_min = XMIN; } if (YMAX != NULL) { y_max = YMAX; } if (YMIN != NULL) { y_min = YMIN; } /* Calculate the x coordinates of the output grid */ xc = (x_max-x_min)/(NUMXOUT-1); for (i = 0 ; i < NUMXOUT ; i++) { xo[i] = i * xc + x_min; } /* Calculate the y coordinates of the output grid */ yc = (y_max-y_min)/(NUMYOUT-1); for (j = 0 ; j < NUMYOUT ; j++) { yo[j] = j * yc + y_min; } /* Set flag for nonlinear interpolation */ c_nnseti("igr",1); /* Run the natural neighbor function */ out = c_natgrids(NUMIN, x, y, z, NUMXOUT, NUMYOUT, xo, yo, &ier); /* Check if any errors were encountered by c_natgrids */ if (ier != 0) { printf (" Error return from c_natgrids = %d\n",ier); } /* Output the results */ for (k = 0; k < NUMXOUT*NUMYOUT; k++) { printf ("%f\n", out[k]); } fclose(in); }