PM nulling bugfix after @vitcpp's PR review.

(and a few minor editorial changes)

Author: msdemlei

expected/epochprop.out

@@ -81,7 +81,7 @@ FROM (
                120) AS tp) AS q;
      to_char     |     to_char     | to_char  | to_char | to_char | to_char  
 -----------------+-----------------+----------+---------+---------+----------
-  269.4520769500 |    5.0388680565 |   23.007 |         |         |  -97.120
+  269.4520769500 |    4.6933649660 |   23.007 |         |         | -110.000
 (1 row)
 
 SELECT epoch_prop(NULL,

src/epochprop.c

@@ -144,28 +144,21 @@ epoch_prop(PG_FUNCTION_ARGS) {
 		input.parallax = 0;
 		output_null[2] = 1;
 		/* The way we do our computation, with a bad parallax the RV
-		will be horribly off, too, so null this out, too */
+		will be horribly off, too, so null this out, too; if avaialble,
+		we will fiddle in the original RV below again. */
 		output_null[5] = 1;
 	} else {
 		input.parallax = PG_GETARG_FLOAT8(1);
 	}
 	input.parallax_valid = fabs(input.parallax) > PX_MIN;
 
-	if (PG_ARGISNULL(2)) {
+	if (PG_ARGISNULL(2) || PG_ARGISNULL(3)) {
 		input.pm[0] = 0;
 		input.pm[1] = 0;
 		output_null[3] = 1;
 		output_null[4] = 1;
 	} else {
 		input.pm[0] = PG_GETARG_FLOAT8(2);
-	}
-
-	if (PG_ARGISNULL(3)) {
-		input.pm[0] = 0;
-		input.pm[1] = 0;
-		output_null[3] = 1;
-		output_null[4] = 1;
-	} else {
 		input.pm[1] = PG_GETARG_FLOAT8(3);
 	}
 

src/epochprop.h

@@ -6,21 +6,12 @@
 extern Datum epoch_prop(PG_FUNCTION_ARGS);
 
 
-/* a cartesian point; this is like geo_decl's point, but you can't
-have both geo_decls and pg_sphere right now (both define a type Point,
-not to mention they have different ideas on EPSILON */
-typedef struct s_cpoint
-{
-	double		x,
-				y;
-} CPoint;
-
 typedef struct s_phasevec
 {
 	SPoint		pos;			/* Position as an SPoint */
 	double		pm[2];			/* Proper motion long/lat in rad/year, PM in
 								 * longitude has cos(lat) applied */
 	double		parallax;		/* in rad */
 	double		rv;				/* radial velocity in km/s */
-	int			parallax_valid; /* 1 if the parallax really is a NULL */
+	int			parallax_valid; /* 1 if we accept the parallax as physical */
 } phasevec;