If you want to understand the maths behind DR, it is simply a method of balancing forces in a dynamic manner (using the velocity and acceleration equivalents of force). I've attached an excerpt from Prof Sigrid Adriaenssen's dissertation that you might find helpful.

The basic idea is for the system in the attached jpg, the equilibrium is P-Ky=0. P is load, K is stiffness and y is displacement/nodal locations, usual Finite Elements stuff. DR models this dynamically so that P - Ky = Fictional Mass x Acceleration + Artificial Damping Coefficient x Velocity. When the right hand side (the Residual Force) of this equation = 0, vibrations have stopped and the corresponding y values represent the equilibrium position.

You iterate by
1) Starting from some y (the initial geometry),
2) Calculate P-Ky by summing all internal forces(prestress) + external applied loads
3) If P - Ky=0, terminate,
4) Calculate velocity and acceleration [you don't really need to know the details of this bit unless you are coding up an algorithm..Sigrid's paper explains it anyways]
5) Find new y based on the given time step and repeat from step 2, first resetting the velocities and accelerations to zero

There are some other specifics, but in plain words this the general idea: apply external forces, calculate the displacement, velocity and acceleration, reset these to zero, reapply external force, recalculate displacement, velocity and acceleration, etc until system has stopped displacing under external force application. Sam Joyce has posted some source code in Processing if you want to see how to program it. http://people.bath.ac.uk/scj21/

Apparently the uploader doesn't like .pdf's so I've attached Sigrid's dissertation excerpt in zipped format. I've had issues opening .ghx files in the past as well; it would be nice if people zipped everything or at the very least checked their uploads because files don't seem to always work when uploaded directly

For a uniform surfaces stress it gives the stable equilibrium shape. I.e I u design a tensile surface to a geometry that is not in equilibrium it will move when u install it causing wrinkles etc. The surface geometry has to be found not dictated. It's one area where engineering can actually drive the aesthetis ;)