Documentation: Vandermonde Example

[KennanHodovic]

Dear team,

Thank you for the extensive work that has gone into this package. I wanted to try and clarify the Vandermonde example (polynomial interpolation) in the documentation so that I may better understand the functionality of this package.

1. The basis modes refer to the number of columns in the matrix but what criteria determines the number we select? Does it refer to every possible sensor location or the regions where sensors can be placed?
2. For the list of data defined as x, is that referring to a list of normalized values or can we input the exact values of the QoI we obtain from simulations? Similarly, is x only defined as a distance or is that just an example and we can input any kind of data?
3. My interest with PySensors is seeing if I can find optimal sensors locations based on data I obtain from a 3D simulated model. Typically, these will not have analytical solutions to compare the reconstruction error too. Is there any other form of validation to provide confidence in where the SSPOR places the sensors?

Thank you for your time and help.

-Kennan Hodovic