LinearInterpolation can access out of bounds with NaN input

[joshuahansel]

Bug Description

In LinearInterpolation, if you do sample(x) and x is a NaN, then it will try and access out of bounds in this:

  auto upper = std::upper_bound(_x.begin(), _x.end(), x);
  int i = std::distance(_x.begin(), upper) - 1;
  return _y[i] + (_y[i + 1] - _y[i]) * (x - _x[i]) / (_x[i + 1] - _x[i]);

If no upper bound exists for x (as in the case of nan), upper = _x.end() and then i = _x.size() - 1, which is a problem for y[i + 1].

Steps to Reproduce

See above.

Impact

Garbage results if nan values are input to object.

[Optional] Diagnostics

No response