Very close number not ish?

[behrica]

I am not understanding a lot on floating points, but it seems to me that these
2 should be "equal" for ish?:

(ish? 1798.4039776258396
         1798.4039776258326)

but they are not.

[emlyn]

Hi Carsten Behring (@behrica),
You need to increase the scale for those to be considered "equal".
By default, numbers are considered equal if they are within the error introduced by operations on numbers in the region of 100 (the scale). If you increase the scale to about a million, it should work:

(set-comparator! (compare-ulp 1e6 2))
(ish? 1798.4039776258396
      1798.4039776258326)  ;; => true

You can find compare-ulp in the same.compare ns.

This should probably be explained better in the README.

[behrica]

Yes, it is still not clear to me which comparator to set, if I want to "tolerate" a certain error.