Alternatives to nullable types in C#

Question

I am writing algorithms that work on series of numeric data, where sometimes, a value in the series needs to be null. However, because this application is performance critical,

Answer 1

Partial answer:

Float and Double provide NaN (Not a Number). NaN is a little tricky since, per spec, NaN != NaN. If you want to know if a number is NaN, you'll need to use Double.IsNaN().

See also Binary floating point and .NET.