L3: Eigendecomposition and principal axes demo doesn't show Q or Lambda

[alpha-tango-kilo]

As the title suggests, regardless as to the values as the sliders and checkboxes, Q and Lambda don't display for the Eigendecomposition and principal axes demo from L3: Covariance and Principal Components

> java --version
java 10.0.2 2018-07-17
Java(TM) SE Runtime Environment 18.3 (build 10.0.2+13)
Java HotSpot(TM) 64-Bit Server VM 18.3 (build 10.0.2+13, mixed mode)

On Windows, using the latest build linked in the README

[alpha-tango-kilo]

Same (or at least similar looking) issue on L6: Local interest points for the structure tensor demo