[Suggestion] Math.lerp and Math.normalize

[WickyNilliams]

Linear extrapolation and normalization are very common operations, particularly for graphics programming. I think they would make good candidates for inclusion in the standard.

For context, both of these are essentially specialisations of the proposed Math.scale, where:

• normalize is equivalent to Math.scale(value, min, max, 0, 1)
• lerp is equivalent to Math.scale(value, 0, 1, min, max)

But they are such common operations, and have their own mathematical names, I think they warrant inclusion.

Math.normalize = function normalize(value, min, max) {
  return (value - min) / (max - min);
};
Math.lerp = function lerp(norm, min, max) {
  return (max - min) * norm + min;
};

console.assert(Math.normalize(15, 10, 20), 0.5)
console.assert(Math.lerp(0.5, 10, 20), 15)

[Rudxain]

I'll list a summary of what I currently know and think about it:

Pros

• Shorter, more concise code
• Possibly a slight performance increase
• Precision-preserving, because less arithmetic is needed to calculate it, and thus less rounding-errors
• Increased likelihood of devs recognizing the methods because of their names

Cons

• Slightly "pollutes" the Math namespace because the methods are easily replaceable
• More names to remember
• Less likelihood to be approved by the comitee, because they're too specialized and defined in terms of another method that's currently a proposal

I think I'm wrong about at least 1 of these, please let me know any mistakes.
I'll add more to both lists if I get requests to do so

[Rudxain]

Petition to add variadic relative normalization:

Math.normRelative = (...values) => {
	const min = Math.min(...values)
	const max = Math.max(...values)
	return values.map(
		x => (x - min) * 2 / (max - min) - 1
	)
}

This scales each value to the range [-1,+1], from a range relative to the minimum and maximum values themselves.

I'm aware that a Math.* method returning an Array is controversial, since every method should return a Number