To leave a variable uninitialized, use the construction:

    int x = void;

Note that nobody is going to write this by accident. And it's easy to grep for.

To find the source of a NaN, it helps to know that every operation that has a NaN as an operand produces a NaN as a result. So if you see a NaN in the output, you can work backwards to where it originated.

▲ jcranmer an hour ago | parent [-]

> every operation that has a NaN as an operand produces a NaN as a result.

That's not true. The minimum/maximum functions (fmin and fminimum_num variants, but not the fminimum one) treat NaN inputs as not-present, so return the non-NaN value if there is one. Similarly, hypot also treats NaN inputs as not-present. pow and compoundn will ignore NaN exponents if the base is 1.

	▲	WalterBright 41 minutes ago \| parent [-]
		Yes, there are some functions where if one operand has no effect on the result, a NaN value will also have no effect.