fix avg of complex

oops, can't avg mod2, duh

libvips/arithmetic/avg.c

@@ -32,6 +32,8 @@
  * 	- remove liboil
  * 24/8/11
  * 	- rewrite as a class
+ * 12/9/14
+ * 	- oops, fix complex avg
  */
 
 /*
@@ -98,17 +100,11 @@ vips_avg_build( VipsObject *object )
 	if( VIPS_OBJECT_CLASS( vips_avg_parent_class )->build( object ) )
 		return( -1 );
 
-	/* Calculate average. For complex, we accumulate re*re +
-	 * im*im, so we need to sqrt.
-	 */
 	vals = (gint64) 
 		vips_image_get_width( statistic->in ) * 
 		vips_image_get_height( statistic->in ) * 
 		vips_image_get_bands( statistic->in );
 	average = avg->sum / vals;
-	if( vips_band_format_iscomplex( 
-		vips_image_get_format( statistic->in ) ) )
-		average = sqrt( average );
 	g_object_set( object, "out", average, NULL );
 
 	return( 0 );
@@ -151,12 +147,10 @@ vips_avg_stop( VipsStatistic *statistic, void *seq )
 	TYPE *p = (TYPE *) in; \
 	\
 	for( i = 0; i < sz; i++ ) { \
-		double mod; \
-		\
-		mod = p[0] * p[0] + p[1] * p[1]; \
-		p += 2; \
+		double mod = sqrt( p[0] * p[0] + p[1] * p[1] ); \
 		\
 		m += mod; \
+		p += 2; \
 	} \
 } 
 

python/test_arithmetic.py

@@ -33,7 +33,7 @@ class TestArithmetic(unittest.TestCase):
         def add12(x):
             return x + 12
 
-        self.assertEqual([add12(x).avg for x in self.test_set], 
+        self.assertEqual([add12(x).avg() for x in self.test_set], 
                          [add12(x) for x in self.avgs])
 
 if __name__ == '__main__':

python/vips8/vips.py

@@ -185,6 +185,8 @@ def _call_base(name, required, optional, self = None, option_string = None):
 
     if len(out) == 1:
         out = out[0]
+    elif len(out) == 0:
+        out = None
 
     # unref everything now we have refs to all outputs we want
     op2.unref_outputs()