html 欧几里德距离计算（http://jsbench.github.io/#245e874d6525184b410369669c05795e）#jsbench #jsperf

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"use strict";

(function (factory) {
	if (typeof Benchmark !== "undefined") {
		factory(Benchmark);
	} else {
		factory(require("benchmark"));
	}
})(function (Benchmark) {
	var suite = new Benchmark.Suite;

	Benchmark.prototype.setup = function () {
		const dist = (v1, v2) => {
			if (v1.length !== v2.length) {
				throw new Error("A vector has extra dimensions.")
			}
		
			if (v1.length < 1) {
				throw new Error("Vectors don't have any dimensions.")
			}
		
			var addedSubtracts = 0
		
			for (let i = 0; i < v1.length; i++) {
				addedSubtracts += Math.pow(v1[i] - v2[i], 2)
			}
		
			return Math.sqrt(addedSubtracts)
		}
		
		const euclideanDistance = (v1, v2) => {
		  if (v1.length !== v2.length) {
		    throw new Error("A vector has extra dimensions.")
		  } else if (v1.length < 1) {
		    throw new Error("Vectors don't have any dimensions.")
		  } else {
		    var scale = 0;
		    var ssq = 1;
		
		    for (var i = 0; i < v1.length; i++) {
		      var x = v1[i] - v2[i];
		      if (x !== 0) {
		          var absx = Math.abs(x);
		          if (scale < absx) {
		              ssq = 1 + ssq * Math.pow(scale / absx, 2);
		              scale = absx;
		          } else {
		              ssq = ssq + Math.pow(absx / scale, 2);
		          }
		      }
		    }
		    return scale * Math.sqrt(ssq);
		  }
		}
	};


	suite.add("Eucli", function () {
		// Eucli
		
		dist([0, 0], [0, 0]);
		dist([1, 0], [0, 0]);
		dist([1], [0]);
		dist([0, 0], [10, 10]);
		dist([10, 12, 8, 4], [87, 76, 92, 1]);
		dist([5, 5, 5], [5, 5, 5]);
		dist([0, 0], [3, 4]);
		dist([3, 4, 5], [5, 5, 5]);
		dist([1, 2, 8, 4], [8, 7, 9, 1]);
	});

	suite.add("Adapted from LAPACK", function () {
		// Adapted from LAPACK
		
		euclideanDistance([0, 0], [0, 0]);
		euclideanDistance([1, 0], [0, 0]);
		euclideanDistance([1], [0]);
		euclideanDistance([0, 0], [10, 10]);
		euclideanDistance([10, 12, 8, 4], [87, 76, 92, 1]);
		euclideanDistance([5, 5, 5], [5, 5, 5]);
		euclideanDistance([0, 0], [3, 4]);
		euclideanDistance([3, 4, 5], [5, 5, 5]);
		euclideanDistance([1, 2, 8, 4], [8, 7, 9, 1]);
	});

	suite.on("cycle", function (evt) {
		console.log(" - " + evt.target);
	});

	suite.on("complete", function (evt) {
		console.log(new Array(30).join("-"));

		var results = evt.currentTarget.sort(function (a, b) {
			return b.hz - a.hz;
		});

		results.forEach(function (item) {
			console.log((idx + 1) + ". " + item);
		});
	});

	console.log("Euclidean distance calculations");
	console.log(new Array(30).join("-"));
	suite.run();
});

<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8"/>
	<title>Euclidean distance calculations</title>
	<script src="https://cdnjs.cloudflare.com/ajax/libs/benchmark/1.0.0/benchmark.min.js"></script>
	<script src="./suite.js"></script>
</head>
<body>
	<h1>Open the console to view the results</h1>
	<h2><code>cmd + alt + j</code> or <code>ctrl + alt + j</code></h2>
</body>
</html>

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