math: add isnan() function

Add a new `isnan()` convenience function to the math library which can
be used to test if a given value is a NaN double.

The same test can be realized without the math library by using a function
similar to the following one:

    function isNaN(x) {
        return x != x;
    }

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

0 files changed, 0 insertions, 0 deletions