--- a
+++ b/inst/op_transform.m
@@ -0,0 +1,11 @@
+function [x2,y2,z2] = op_transform(x1,y1,z1,param1,param2)
+
+if strfind(param1,'+proj=latlong')
+    x1 = x1*pi/180.0;
+    y1 = y1*pi/180.0;
+end
+[x2,y2,z2] = _op_transform(x1,y1,z1,param1,param2);
+if strfind(param2,'+proj=latlong')
+    x2 = x2*180.0/pi;
+    y2 = y2*180.0/pi;
+end