How to directly generate inverse kinematics solution?

edit

Hi, I am trying to use solve forword and inverse kinematics for my robot arm. I have a 6 DOF arm and already have the urdf file ready.

My propose is only forward kinematics and inverse kinematics. This is what I want to achieve: 1. Given each joints' angle, output the end effector's position/rotation. 2. Given end effector's position/rotation, compute the angle for each joint.

Can some one give me some hints on a simple way to do it? I am now following the MoveIt! tutorial and try to implememnt FastIK, but I think most of its functions are not needed for me, I do not really need to visulization or do motion planning. Is arm_navigation a better package(I need to change my ROS version to use it)?