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Is there an isnan() function?
PS.: I'm in MinGW (if that makes a difference).
I had this solved by using isnan() from <math.h>, which doesn't exist in <cmath>, which I was #includeing at first.
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NaN stands for Not A Number and is one of the common ways to represent the missing value in the data. It is a special floating-point value and cannot be converted to any other type than float. NaN value is one of the major problems in Data Analysis.
The NaN values are used to identify undefined or non-representable values for floating-point elements, such as the square root of negative numbers or the result of 0/0. In C, this is implemented as a macro that returns an int value.
Sure! NaN is a static constant in the Float and Double classes.
The nan() function in C++ returns a quiet NaN (Not-A-Number) value of type double. The function is defined in <cmath> header file.
According to the IEEE standard, NaN values have the odd property that comparisons involving them are always false. That is, for a float f, f != f will be true only if f is NaN.
Note that, as some comments below have pointed out, not all compilers respect this when optimizing code.
For any compiler which claims to use IEEE floating point, this trick should work. But I can't guarantee that it will work in practice. Check with your compiler, if in doubt.
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