Stats Regression ivoptions gethashcode

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IvOptions.GetHashCode

A hash consistent with the generated equality, with every NaN hashed alike.

public int GetHashCode()

Returns — a hash over every member, each double through one rule that sends every NaN to the same value.

Example — a NaN and its negation are different bit patterns, and still equal and hash alike.

using Lodestar.Stats.Regression.Instrumental;

IvOptions left = new() { Fuller = double.NaN };
IvOptions right = new() { Fuller = -double.NaN };

bool equal = left.Equals(right);                          // => True
bool alike = left.GetHashCode() == right.GetHashCode();  // => True

Remarks — the equality stays the one the compiler generates, under which every NaN equals every other. .NET Framework, Mono and Unity hash a NaN's sign and payload bits, so without this override two equal values could hash apart there and miss each other in a Dictionary or a HashSet (#1285).

Applies to — net10.0, netstandard2.0.

See also — IvOptions.