What is the test for obviousness as announced in the landmark case, Graham v. John Deere?

According to Graham v. John Deere Co.,  383 U.S. 1 (1966), in order to determine whether a claim would have been obvious to a person of ordinary skill in the art at the time the invention was made, a court is to carefully consider the following:

1. the scope and content of the prior art;
2. the differences between the claimed invention and that prior art; and
3. the level of ordinary skill in the art.

In addition, the Graham Court mentioned number of “secondary considerations” which could serve as evidence of non-obviousness. These secondary considerations include:

1. the commercial success of the claimed invention;
2. whether the claimed invention satisfied a long felt but unsolved need; and
3. the failure of others to solve the problem that the claimed invention solved.