1 files changed, 173 insertions, 0 deletions
diff --git a/lib/math.c b/lib/math.c
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+/* math.c: define some simple array operations, and other functions.
+
+Copyright (C) 1992 Free Software Foundation, Inc.
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program; if not, write to the Free Software
+Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+#include "config.h"
+
+
+/* Numerical errors sometimes make a floating point number just slightly
+   larger or smaller than its true value.  When it matters, we need to
+   compare with some tolerance, REAL_EPSILON, defined in kbase.h.  */
+
+const boolean
+epsilon_equal (real v1, real v2)
+{
+  return
+    v1 == v2		       /* Usually they'll be exactly equal, anyway.  */
+    || fabs (v1 - v2) <= REAL_EPSILON;
+}
+
+
+/* Return the Euclidean distance between P1 and P2.  */
+
+const real
+distance (real_coordinate_type p1, real_coordinate_type p2)
+{
+  return hypot (p1.x - p2.x, p1.y - p2.y);
+}
+
+
+/* Same thing, for integer points.  */
+const real
+int_distance (coordinate_type p1, coordinate_type p2)
+{
+  return hypot ((double) p1.x - p2.x, (double) p1.y - p2.y);
+}
+
+
+/* Return the arc cosine of V, in degrees in the range zero to 180.  V
+   is taken to be in radians.  */
+
+const real
+acosd (real v)
+{
+  real a;
+
+  if (epsilon_equal (v, 1.0))
+    v = 1.0;
+  else if (epsilon_equal (v, -1.0))
+    v = -1.0;
+
+  errno = 0;
+  a = acos (v);
+  if (errno == ERANGE || errno == EDOM)
+    FATAL_PERROR ("acosd");
+
+  return a * 180.0 / M_PI;
+}
+
+
+/* The slope of the line defined by COORD1 and COORD2.  */
+
+const real
+slope (real_coordinate_type coord1, real_coordinate_type coord2)
+{
+  assert (coord2.x - coord1.x != 0);
+
+  return (coord2.y - coord1.y) / (coord2.x - coord1.x);
+}
+
+
+/* Turn an integer point into a real one, and vice versa.  */
+
+const real_coordinate_type
+int_to_real_coord (coordinate_type int_coord)
+{
+  real_coordinate_type real_coord;
+
+  real_coord.x = int_coord.x;
+  real_coord.y = int_coord.y;
+
+  return real_coord;
+}
+
+
+const coordinate_type
+real_to_int_coord (real_coordinate_type real_coord)
+{
+  coordinate_type int_coord;
+
+  int_coord.x = ROUND (real_coord.x);
+  int_coord.y = ROUND (real_coord.y);
+
+  return int_coord;
+}
+
+
+/* See if two points (described by their row and column) are adjacent.  */
+
+const boolean
+points_adjacent_p (int row1, int col1, int row2, int col2)
+{
+  int row_diff = abs (row1 - row2);
+  int col_diff = abs (col1 - col2);
+
+  return
+    (row_diff == 1 && col_diff == 1)
+    || (row_diff == 0 && col_diff == 1)
+    || (row_diff == 1 && col_diff == 0);
+}
+
+
+
+
+/* Find the largest and smallest elements in an array of reals.  */
+
+void
+find_bounds (real *values, unsigned value_count, real *min, real *max)
+{
+  unsigned this_value;
+
+  /* We must use FLT_MAX and FLT_MIN, instead of the corresponding
+     values for double, because gcc uses the native atof to parse
+     floating point constants, and many atof's choke on the extremes.  */
+  *min = FLT_MAX;
+  *max = FLT_MIN;
+
+  for (this_value = 0; this_value < value_count; this_value++)
+    {
+      if (values[this_value] < *min)
+	*min = values[this_value];
+
+      if (values[this_value] > *max)
+	*max = values[this_value];
+    }
+}
+
+
+
+/* Map a range of numbers, some positive and some negative, into all
+   positive, with the greatest being at one and the least at zero.
+
+   This allocates new memory.  */
+
+real *
+map_to_unit (real *values, unsigned value_count)
+{
+  real smallest, largest;
+  int this_value;
+  real *mapped_values = xmalloc (sizeof (real) * value_count);
+
+  find_bounds (values, value_count, &smallest, &largest);
+
+  largest -= smallest;		/* We never care about largest itself. */
+
+  for (this_value = 0; this_value < value_count; this_value++)
+    mapped_values[this_value] = (values[this_value] - smallest) / largest;
+
+  return mapped_values;
+}