71 lines
2.0 KiB
JavaScript
71 lines
2.0 KiB
JavaScript
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import { factory } from '../../utils/factory.js';
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import { deepMap } from '../../utils/collection.js';
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import { log2Number } from '../../plain/number/index.js';
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var name = 'log2';
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var dependencies = ['typed', 'config', 'Complex'];
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export var createLog2 = /* #__PURE__ */factory(name, dependencies, _ref => {
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var {
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typed,
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config,
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Complex
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} = _ref;
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/**
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* Calculate the 2-base of a value. This is the same as calculating `log(x, 2)`.
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*
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* For matrices, the function is evaluated element wise.
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*
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* Syntax:
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*
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* math.log2(x)
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*
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* Examples:
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*
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* math.log2(0.03125) // returns -5
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* math.log2(16) // returns 4
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* math.log2(16) / math.log2(2) // returns 4
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* math.pow(2, 4) // returns 16
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*
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* See also:
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*
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* exp, log, log1p, log10
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*
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* @param {number | BigNumber | Complex | Array | Matrix} x
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* Value for which to calculate the logarithm.
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* @return {number | BigNumber | Complex | Array | Matrix}
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* Returns the 2-base logarithm of `x`
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*/
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return typed(name, {
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number: function number(x) {
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if (x >= 0 || config.predictable) {
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return log2Number(x);
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} else {
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// negative value -> complex value computation
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return _log2Complex(new Complex(x, 0));
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}
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},
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Complex: _log2Complex,
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BigNumber: function BigNumber(x) {
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if (!x.isNegative() || config.predictable) {
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return x.log(2);
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} else {
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// downgrade to number, return Complex valued result
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return _log2Complex(new Complex(x.toNumber(), 0));
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}
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},
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'Array | Matrix': function ArrayMatrix(x) {
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return deepMap(x, this);
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}
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});
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/**
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* Calculate log2 for a complex value
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* @param {Complex} x
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* @returns {Complex}
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* @private
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*/
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function _log2Complex(x) {
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var newX = Math.sqrt(x.re * x.re + x.im * x.im);
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return new Complex(Math.log2 ? Math.log2(newX) : Math.log(newX) / Math.LN2, Math.atan2(x.im, x.re) / Math.LN2);
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}
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});
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