Changeset 38873 for trunk/psphot/src

Timestamp:

Oct 17, 2015, 6:06:53 AM (11 years ago)

Author:

eugene

Message:

fix comments re: M3c, M3s, M4c, M4s

File:

• trunk/psphot/src/psphotImageQuality.c (modified) (1 diff)

trunk/psphot/src/psphotImageQuality.c

@@ -98 +98 @@
         // r^2 sin(2t) = r^2 2 cos t sin t = 2 x y
 
-        // r^3 cos(3t) = r^3 cos^3 t - r^2 3 cos t sin^2 t = (x^3 - 3 x y^2)
-        // r^3 sin(3t) = r^3 3 cos^2 t sin t - sin^3 t = (3 x^2 y - y^3)
-
-        // r^4 cos(4t) = r^4 cos^4 t - r^2 6 cos^2 t sin^2 t + r^2 sin^4 t = (x^4 - 6 x^2 y^2 + y^4)
-        // r^4 sin(4t) = r^4 4 cos^3 t sin t - 4 sin^3 t cos t = (4 x^3 y - 4 y^3 x)
+        // r^2 cos(3t) = r^2 cos^3 t - r^2 3 cos t sin^2 t = (x^3 - 3 x y^2) / r
+        // r^2 sin(3t) = r^2 3 cos^2 t sin t - sin^3 t = (3 x^2 y - y^3) / r
+
+        // r^2 cos(4t) = r^2 cos^4 t - r^2 6 cos^2 t sin^2 t + r^2 sin^4 t = (x^4 - 6 x^2 y^2 + y^4) / r^2
+        // r^2 sin(4t) = r^2 4 cos^3 t sin t - 4 sin^3 t cos t = (4 x^3 y - 4 y^3 x) / r^2
+
+        // NOTE that Mxxx,etc have the factor of r in the denominator, while Mxxxx,etc have the factor of r^2.
+        // See pmSourceMoments.c:418
 
         num++;