Implemented the positive definiteness cost function
Fixed the sign of the cost for p.d. mats
Added gitignore
Changed the sign of the cost function to give cleaner code.

We need the opposite sign to *minimize* the cost, but we can add that in later.
Changed the sign of the cost function for clarity.

We need the opposite sign to *minimize* the cost, but we can add that in
later.
Merge branch 'pos-def-constraint' of github.com:medthehatta/thesis-code into pos-def-constraint
Added the utility functions for testing