Integrate with Views Simple Math Field

Problem/Motivation

I am trying to allow the user to enable or disable fields, and calculate a total from the resulting fields using Views Simple Math Field → module.

Steps to reproduce

1. Add a "Global: On/Off Form" field and enable for a few fields:
   
2. Add a "Global: Simple Math" field and calculate the result, like this:
   
3. Expect disabled fields to not be included in the calculation, but see that they are

Show all fields

Only field Rank3 enabled, expected result

Unit C at the top with 0.99.

Only field Rank3 enabled, actual result

All values are used in calculation, Unit C still at position #3.

Proposed resolution

Exclude values in "Simple Math Field" field calculations which are disabled via "On/Off Form" field.

Remaining tasks

User interface changes

API changes

Data model changes