You can test if your implementation has it: #include <math.h> #ifdef NAN /* NAN is supported */ #endif #ifdef INFINITY /* INFINITY is supported */ #endif The existence of INFINITY is guaranteed by C99 (or the latest draft at least), and “expands to a constant expression of type float representing positive or unsigned infinity, if … Read more
This behavior is due to the /fp:fast MSVC compiler option, which (among other things) permits the compiler to perform comparisons without regard to proper NaN behavior in an effort to generate faster code. Using /fp:precise or /fp:strict instead causes these comparisons to behave as expected when presented with NaN arguments.
>>> numpy.nan is numpy.NaN is numpy.NAN True It’s just convenient. They’re exactly the same.
Java specifies that floating point numbers follow the IEEE 754 standard. This is how it’s stored: bit 0 : sign bit bits 1 to 11 : exponent bits 12 to 63 : fraction Now, I have executed below method with different double values: public static void print(double d){ System.out.println(Long.toBinaryString(Double.doubleToRawLongBits(d))); } I executed with these values: … Read more
Looking at <cmath> for libstdc++ shipped with gcc 4.9 you get this: constexpr bool isnan(double __x) { return __builtin_isnan(__x); } A constexpr function could be aggressively inlined and, of course, the function just delegates the work over to __builtin_isnan. The <math.h> header doesn’t use __builtin_isnan, rather it uses an __isnan implementation which is kind of … Read more
Both describe and info report the count of non-missing values. In [1]: df = DataFrame(np.random.randn(10,2)) In [2]: df.iloc[3:6,0] = np.nan In [3]: df Out[3]: 0 1 0 -0.560342 1.862640 1 -1.237742 0.596384 2 0.603539 -1.561594 3 NaN 3.018954 4 NaN -0.046759 5 NaN 0.480158 6 0.113200 -0.911159 7 0.990895 0.612990 8 0.668534 -0.701769 9 -0.607247 … Read more
NaN‘s are unusual: they are not equal to anything, even themselves. You need to use isNaN(inbperr) to tell whether a value is a NaN or not.
The previous answers are useful, but perhaps not clear regarding the root of the problem. In any language, sort applies a given ordering, defined by a comparison function or in some other way, over the domain of the input values. For example, less-than, a.k.a. operator <, could be used throughout if and only if less … Read more
There is in C99, but not in previous standards AFAIK. In C99, you’ll have NAN and INFINITY macros. From “Mathematics <math.h>“ (§7.12) section The macro INFINITY expands to a constant expression of type float representing positive or unsigned infinity, if available; … If you’re stuck with ANSI C89, you’re out of luck. See C-FAQ 14.9.