Is it a good idea to use IEEE754 floating point NaN for values which are not set?

Question

Is it a good idea to use IEEE754 floating point NaN (not-a-number) for values which are undefined for non-mathematical reasons?

In our case they are not yet set beca

Answer 1

Be careful with NaN's... they can spread like wildfire if you are not careful.

They are a perfectly valid value for floats, but any assignments involving them will also equal NaN, so they propagate through your code. This is quite good as a debugging tool if you catch it, however it can also be a real nuisance if you are bringing something to release and there is a fringe case somewhere.

D uses this as rationale for giving floats NaN as default. (Which I'm not sure I agree with.)