17 #include <grass/gis.h>
20 static struct Cell_head
window;
21 static double square_meters;
22 static int projection;
24 static double units_to_meters_squared = 0.0;
28 static double north_value;
30 static double (*darea0) (double);
56 switch (projection =
window.proj) {
68 north_value = darea0(north =
window.north);
74 square_meters *= (factor * factor);
75 return (factor > 0.0);
93 register double south_value;
94 register double cell_area;
96 if (projection != PROJECTION_LL)
100 north_value = darea0(north =
window.north - row *
window.ns_res);
102 south_value = darea0(north -=
window.ns_res);
103 cell_area = north_value - south_value;
106 north_value = south_value;
135 units_to_meters_squared = factor * factor;
138 units_to_meters_squared = 1.0;
169 if (projection == PROJECTION_LL)