### Summary
This paper introduces a much faster method of cloth simulation via implicit numerical integration using the conjugate gradient method.  It also gives a method for resolving constraints to the simulations.
### Problem
Since cloth resists stretching, but largely permits bending, the differential equations governing it are "stiff," making them ill-suited for explicit integration.  
### Methods Used
* Stepping time forward with implicit integration
* The conjugate gradient method to solve the sparse linear system
* A new method to enforce constraints where the particle to be constrained's mass is set to infinity and a solution is obtained as normal
### Key Ideas
* It's feasible to use implicit integration for cloth simulation
* The conjugate gradient method is a good candidate for this type of simulation
* A novel method to enforce constraints