cmake support preparation: use of INFINITY and NAN (OSGeo#2681)

* cmake support preparation: use of INFINITY and NAN

- use of `INFINITY` rather than only division by zero (this is supported by gcc and other compilers but not on Windows)
- use of `NAN` rather than only division by zero

Extracted from WIP PR OSGeo#289

Further changes on top:

- fix indentation
- revert void* arithmetic change
- remove superfluous comments
- use 0 (zero) to init integers
- 0/0 = NAN, 1/0 = INFINITY
- Include math.h for Windows
- Use c++ include
- r.series: add INFINITY
- apply clang-format to match reformatting in `main` by using `for i in $(gh pr view 2681 --json files --jq '.files.[].path') ; do clang-format -i $i ; done`

Co-authored-by: @rkanavath
Co-authored-by: @nilason

Author: neteler

general/g.region/printwindow.c

@@ -469,7 +469,7 @@ void print_window(struct Cell_head *window, int print_flag, int flat_flag)
         double convergence;
 
         if (G_projection() == PROJECTION_XY)
-            convergence = 0. / 0.;
+            convergence = NAN;
         else if (G_projection() == PROJECTION_LL)
             convergence = 0.0;
         else {

lib/btree2/kdtree.c

@@ -531,7 +531,7 @@ int kdtree_knn(struct kdtree *t, double *c, int *uid, double *d, int k,
     if (skip)
         sn.uid = *skip;
 
-    maxdist = 1.0 / 0.0;
+    maxdist = INFINITY;
     found = 0;
 
     /* go down */

lib/gmath/la.c

@@ -1291,7 +1291,7 @@ double G_vector_norm1(vec_struct *vc)
 
     if (!vc->is_init) {
         G_warning(_("Matrix is not initialised"));
-        return 0.0 / 0.0; /* NaN */
+        return NAN;
     }
 
     idx = (vc->v_indx > 0) ? vc->v_indx : 0;

lib/vector/Vlib/box.c

@@ -248,7 +248,7 @@ int Vect_get_line_box(const struct Map_info *Map, int line,
 
     Line = Plus->Line[line];
     if (Line == NULL) { /* dead */
-        Box->N = Box->S = Box->E = Box->W = Box->T = Box->B = 0. / 0.;
+        Box->N = Box->S = Box->E = Box->W = Box->T = Box->B = NAN;
         return 0;
     }
 
@@ -313,7 +313,7 @@ int Vect_get_area_box(const struct Map_info *Map, int area,
     Area = Plus->Area[area];
 
     if (Area == NULL) { /* dead */
-        Box->N = Box->S = Box->E = Box->W = Box->T = Box->B = 0. / 0.;
+        Box->N = Box->S = Box->E = Box->W = Box->T = Box->B = NAN;
         return 0;
     }
 
@@ -360,7 +360,7 @@ int Vect_get_isle_box(const struct Map_info *Map, int isle,
     Isle = Plus->Isle[isle];
 
     if (Isle == NULL) { /* dead */
-        Box->N = Box->S = Box->E = Box->W = Box->T = Box->B = 0. / 0.;
+        Box->N = Box->S = Box->E = Box->W = Box->T = Box->B = NAN;
         return 0;
     }
 

raster/r.horizon/main.c

@@ -754,7 +754,7 @@ double horizon_height(void)
 {
     double height;
 
-    tanh0 = -1.0 / 0.0; /* -inf */
+    tanh0 = -INFINITY;
     length = 0;
 
     height = searching();

raster/r.in.bin/main.c

@@ -254,7 +254,7 @@ int main(int argc, char *argv[])
     const char *outpre;
     char output[GNAME_MAX];
     const char *title;
-    double null_val = 0.0 / 0.0;
+    double null_val = NAN;
     int is_fp;
     int is_signed;
     int bytes, hbytes;

raster/r.in.lidar/info.c

@@ -12,11 +12,9 @@
  */
 
 #include <string.h>
-
+#include <math.h>
 #include <grass/glocale.h>
-
 #include <liblas/capi/liblas.h>
-
 #include "local_proto.h"
 
 void print_lasinfo(LASHeaderH LAS_header, LASSRSH LAS_srs)
@@ -99,7 +97,7 @@ int scan_bounds(LASReaderH LAS_reader, int shell_style, int extents, int update,
     first = TRUE;
 
     /* init to nan in case no points are found */
-    min_x = max_x = min_y = max_y = min_z = max_z = 0.0 / 0.0;
+    min_x = max_x = min_y = max_y = min_z = max_z = NAN;
 
     G_verbose_message(_("Scanning data ..."));
 

raster/r.in.pdal/info.cpp

@@ -10,14 +10,15 @@
  */
 
 #include "info.h"
+#include <cmath>
 
 void get_extent(struct StringList *infiles, double *min_x, double *max_x,
                 double *min_y, double *max_y, double *min_z, double *max_z)
 {
     pdal::StageFactory factory;
     bool first = 1;
 
-    *min_x = *max_x = *min_y = *max_y = *min_z = *max_z = 0.0 / 0.0;
+    *min_x = *max_x = *min_y = *max_y = *min_z = *max_z = NAN;
 
     for (int i = 0; i < infiles->num_items; i++) {
         const char *infile = infiles->items[i];

raster/r.in.xyz/main.c

@@ -124,8 +124,8 @@ int main(int argc, char *argv[])
     int arr_row, arr_col;
     unsigned long count, count_total;
 
-    double min = 0.0 / 0.0; /* init as nan */
-    double max = 0.0 / 0.0; /* init as nan */
+    double min = NAN;
+    double max = NAN;
     double zscale = 1.0;
     double vscale = 1.0;
     size_t offset, n_offset;

raster/r.li/r.li.padrange/padrange.c

@@ -312,8 +312,8 @@ int calculate(int fd, struct area_entry *ad, double *result)
                       (((NS_DIST1 + NS_DIST2) / 2) / hd.rows);
 
         /* get min and max patch size */
-        min = 1.0 / 0.0;  /* inf */
-        max = -1.0 / 0.0; /* -inf */
+        min = INFINITY;
+        max = -INFINITY;
         for (old_pid = 1; old_pid <= pid; old_pid++) {
             if (pst[old_pid].count > 0) {
                 area_p = cell_size_m * pst[old_pid].count / 10000;
@@ -549,8 +549,8 @@ int calculateD(int fd, struct area_entry *ad, double *result)
                       (((NS_DIST1 + NS_DIST2) / 2) / hd.rows);
 
         /* get min and max patch size */
-        min = 1.0 / 0.0;  /* inf */
-        max = -1.0 / 0.0; /* -inf */
+        min = INFINITY;
+        max = -INFINITY;
         for (old_pid = 1; old_pid <= pid; old_pid++) {
             if (pst[old_pid].count > 0) {
                 area_p = cell_size_m * pst[old_pid].count / 10000;
@@ -786,8 +786,8 @@ int calculateF(int fd, struct area_entry *ad, double *result)
                       (((NS_DIST1 + NS_DIST2) / 2) / hd.rows);
 
         /* get min and max patch size */
-        min = 1.0 / 0.0;  /* inf */
-        max = -1.0 / 0.0; /* -inf */
+        min = INFINITY;
+        max = -INFINITY;
         for (old_pid = 1; old_pid <= pid; old_pid++) {
             if (pst[old_pid].count > 0) {
                 area_p = cell_size_m * pst[old_pid].count / 10000;