> But one should expect a single function does not vary in the last 5 digits as one example did. That's over 16 bits. 0.9999999999999999999999999999999

> But one should expect a single function does not vary in the last 5 digits as one example did. That's over 16 bits. 0.9999999999999999999999999999999 1.0000000000000000000000000000000 Counting the number of different digits has no useful meaning. The example you cite has two results that differ by 1 part in 10 quadrillion. If you have a good reason care about the precise implementation of hyperbolic functions to that level of precision then you don't rely on whatever you happen to stumble on in some version of nodejs.