spoint_dwithin: Use FPle, add tests

Author: df7cb

expected/points.out

@@ -666,3 +666,19 @@ SELECT '( 0h 2m 30s , -90d 0m 0s)'::spoint<->'( 12h 2m 30s , -90d 0m 0s)'::spoin
         0
 (1 row)
 
+-- spoint_dwithin function ----------
+SELECT a, b, radius, a <-> b AS "<->", spoint_dwithin(a, b, radius)
+FROM (VALUES
+      ('(0, 0)'::spoint, '(0, 0)'::spoint, 0),
+      ('(0, 0)', '(0, 1)', 1),
+      ('(0, 0)', '(0.1, 0.1)', 0.14),
+      ('(0, 0)', '(0.1, 0.1)', 0.15)
+     ) sub (a, b, radius);
+    a    |      b      | radius |       <->       | spoint_dwithin 
+---------+-------------+--------+-----------------+----------------
+ (0 , 0) | (0 , 0)     |      0 |               0 | t
+ (0 , 0) | (0 , 1)     |      1 |               1 | t
+ (0 , 0) | (0.1 , 0.1) |   0.14 | 0.1413032986961 | f
+ (0 , 0) | (0.1 , 0.1) |   0.15 | 0.1413032986961 | t
+(4 rows)
+

sql/points.sql

@@ -240,3 +240,12 @@ SELECT '( 0h 2m 30s , 90d 0m 0s)'::spoint<->'( 12h 2m 30s , 90d 0m 0s)'::spoint;
 
 SELECT '( 0h 2m 30s , -90d 0m 0s)'::spoint<->'( 12h 2m 30s , -90d 0m 0s)'::spoint;
 
+-- spoint_dwithin function ----------
+
+SELECT a, b, radius, a <-> b AS "<->", spoint_dwithin(a, b, radius)
+FROM (VALUES
+      ('(0, 0)'::spoint, '(0, 0)'::spoint, 0),
+      ('(0, 0)', '(0, 1)', 1),
+      ('(0, 0)', '(0.1, 0.1)', 0.14),
+      ('(0, 0)', '(0.1, 0.1)', 0.15)
+     ) sub (a, b, radius);

src/point.c

@@ -232,7 +232,7 @@ spherepoint_dwithin(PG_FUNCTION_ARGS)
 	float8		within = PG_GETARG_FLOAT8(2);
 	float8		dist = spoint_dist(p1, p2);
 
-	PG_RETURN_BOOL(dist <= within);
+	PG_RETURN_BOOL(FPle(dist, within));
 }