Example program for dsptri

This example computes the inverse of the matrix A, where
A= 2.07 3.87 4.20 -1.15 3.87 -0.21 1.87 0.63 4.20 1.87 1.15 2.06 -1.15 0.63 2.06 -1.81 .  
Here A is symmetric indefinite, stored in packed form, and must first be factorized by dsptrf.