Inline angle_between

2 files changed, 9 insertions, 12 deletions

diff --git a/src/utils.c b/src/utils.c
index c22bce71..de02ee6e 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -16,16 +16,6 @@
 #include "utils.h"
 
 
-/* Angle between two vectors.  Answer in radians */
-double angle_between(double x1, double y1, double z1,
-                     double x2, double y2, double z2)
-{
-	double mod1 = modulus(x1, y1, z1);
-	double mod2 = modulus(x2, y2, z2);
-	return acos( (x1*x2 + y1*y2 + z1*z2) / (mod1*mod2) );
-}
-
-
 size_t skipspace(const char *s)
 {
 	size_t i;
diff --git a/src/utils.h b/src/utils.h
index 9aa07c8c..081d5a71 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -64,8 +64,6 @@ extern int quaternion_valid(struct quaternion q);
 
 /* --------------------------- Useful functions ----------------------------- */
 
-extern double angle_between(double x1, double y1, double z1,
-                            double x2, double y2, double z2);
 extern size_t skipspace(const char *s);
 extern void chomp(char *s);
 extern void progress_bar(int val, int total, const char *text);
@@ -102,6 +100,15 @@ static inline double distance3d(double x1, double y1, double z1,
 	return modulus(x1-x2, y1-y2, z1-z2);
 }
 
+/* Answer in radians */
+static inline double angle_between(double x1, double y1, double z1,
+                  double x2, double y2, double z2)
+{
+	double mod1 = modulus(x1, y1, z1);
+	double mod2 = modulus(x2, y2, z2);
+	return acos( (x1*x2 + y1*y2 + z1*z2) / (mod1*mod2) );
+}
+
 
 /* ----------------------------- Useful macros ------------------------------ */