question: void yrot ( double theta ) { theta *= ( pi / 180 ) ; double ct = Math . cos ( theta ) ; double st = Math . sin ( theta ) ; float Nxx = ( float ) ( xx * ct + zx * st ) ; float Nxy = ( float ) ( xy * ct + zy * st ) ; float Nxz = ( float ) ( xz * ct + zz * st ) ; float Nxo = ( float ) ( xo * ct + zo * st ) ; float Nzx = ( float ) ( zx * ct - xx * st ) ; float Nzy = ( float ) ( zy * ct - xy * st ) ; float Nzz = ( float ) ( zz * ct - xz * st ) ; float Nzo = ( float ) ( zo * ct - xo * st ) ; xo = Nxo ; xx = Nxx ; xy = Nxy ; xz = Nxz ; zo = Nzo ; zx = Nzx ; zy = Nzy ; zz = Nzz ; }
target:  rotate theta degrees about the y axis 