Improve Irrational vs BigFloat comparisons #29196
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This creates a fast path via Float64, and falls back on extended precision only when necessary. It also adds a loop to deal with potential edge cases.
stevengj
reviewed
Sep 15, 2018
| elseif cmp(x, Float64(y, RoundUp)) > 0 | ||
| return +1 | ||
| else | ||
| for prec in Iterators.countfrom(precision(x), 32) |
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This seems dangerous, since if someone defines an "irrational" constant that is actually rational it will never terminate.
How about just something for prec in (precision(x), max(precision(x), precision(BigFloat)) + 32) and return 0 if both of these report equality.
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I'm not sure I agree: that would only occur if (a) you define an irrational as a rational value, and (b) compare it to that same rational. I'm not really sure.
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See #26550 for why some AbstractIrrational subtypes may define rational values.
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This creates a fast path via Float64, and falls back on extended precision only when necessary. It also adds a loop to deal with potential edge cases.