Re: [Python-ideas] Consider adding clip or clamp function to math

clamp(val, lo, hi) should raise ValueError if either lo or hi is NaN,

NaN and ValueError are kind of redundant. NaN exists as a way to (kind of) propagate value errors within the hardware floating point machinery. So it _might_ make sense for Python to raise ValueError wherever a NaN shows up, but as long as, e.g. X * NaN Returns NaN, so should clamp() or clip() or whatever it's called. Greg spelled it all out, but in short: If a NaN is passed in anywhere, you get a NaN back. One could argue that: clamp(NaN, x,x) Is clearly defined as x. But that would require special casing, and, "equality" is a bit of an ephemeral concept with floats, so better to return NaN. -CHB