--- ray/src/gen/surf.cal	1991/11/12 17:05:16	2.1
+++ ray/src/gen/surf.cal	1998/07/09 13:06:21	2.2
@@ -10,9 +10,9 @@
 	A11 A12 A13	/
 }
 
+surf_u = select(arg(1)+1, Py, Pz, Px);
+surf_v = select(arg(1)+1, Pz, Px, Py);
+
 surf_dx = surf_u*surf_v*arg(2) + surf_u*arg(5) + surf_v*arg(8) + arg(11);
 surf_dy = surf_u*surf_v*arg(3) + surf_u*arg(6) + surf_v*arg(9) + arg(12);
 surf_dz = surf_u*surf_v*arg(4) + surf_u*arg(7) + surf_v*arg(10) + arg(13);
-
-surf_u = select(arg(1)+1, Py, Pz, Px);
-surf_v = select(arg(1)+1, Pz, Px, Py);