how to rotate about an axis say axisY in code example WaveMachine.ejs found here http://www.compadre.org/osp/items/detail.cfm?ID=10481 ?

attached is my attempt to create drawings of masses on the tip of the rods but i can seem to get the codes right for rotating about the Y axis.

referring to http://fem.um.es/Javadoc/OSP_EJS/org/opensourcephysics/numerics/Matrix3DTransformation.html#rotation%28double,%20double[]%29

i tried rotationsYaxis[i] = Matrix3DTransformation.rotation(theta[i],axisY);

and other permutations of codes but just could not get the masses to rotate as if they were attached on the tips of the rods.

the reason i need this is to create situations similar to http://www.nationalstemcentre.org.uk/elibrary/resource/2096/wave-machine/
to illustrate wave speed through different medium

thanks!

Attached File: ejs_WaveMachinewee.zip

http://weelookang.blogspot.sg