问题
I have :
double score = cvMatchContourTrees( CT1, CT2, CV_CONTOUR_TREES_MATCH_I1, 0.0 );
cout<<score<<endl;
There are values returned as -1.#IND. Other than that, the positive values are normal, like 1.34543.
Why does this happen? How do I solve it?
回答1:
As Frederic says, it's the result of a 'Not a Number' being formatted by an application built with visual studio on windows. John D Cook has an excellent reference:
Windows displays a NaN as -1.#IND ("IND" for "indeterminate") while Linux displays nan.
...
In short, if you get 1.#INF or inf, look for overflow or division by zero. If you get 1.#IND or nan, look for illegal operations.
Watch out for truncations if you do any sort of formatting with your string; I've encountered related issues when handling these sorts of errors myself.
回答2:
std::cout << (0/0.f);
// Output: -1.#IND
It's NaN.
回答3:
In my experience -1.#IND comes from imaginary numbers. So, doing cout << sqrt(-1.); should output -1.#IND
来源：https://stackoverflow.com/questions/7476177/why-are-the-return-values-of-these-doubles-1-ind