1 | import { factory } from '../../utils/factory.js';
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2 | import { deepMap } from '../../utils/collection.js';
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3 | import { log2Number } from '../../plain/number/index.js';
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4 | var name = 'log2';
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5 | var dependencies = ['typed', 'config', 'Complex'];
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6 | export var createLog2 = /* #__PURE__ */factory(name, dependencies, (_ref) => {
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7 | var {
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8 | typed,
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9 | config,
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10 | Complex
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11 | } = _ref;
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12 |
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13 | /**
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14 | * Calculate the 2-base of a value. This is the same as calculating `log(x, 2)`.
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15 | *
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16 | * For matrices, the function is evaluated element wise.
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17 | *
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18 | * Syntax:
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19 | *
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20 | * math.log2(x)
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21 | *
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22 | * Examples:
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23 | *
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24 | * math.log2(0.03125) // returns -5
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25 | * math.log2(16) // returns 4
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26 | * math.log2(16) / math.log2(2) // returns 4
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27 | * math.pow(2, 4) // returns 16
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28 | *
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29 | * See also:
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30 | *
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31 | * exp, log, log1p, log10
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32 | *
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33 | * @param {number | BigNumber | Complex | Array | Matrix} x
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34 | * Value for which to calculate the logarithm.
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35 | * @return {number | BigNumber | Complex | Array | Matrix}
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36 | * Returns the 2-base logarithm of `x`
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37 | */
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38 | return typed(name, {
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39 | number: function number(x) {
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40 | if (x >= 0 || config.predictable) {
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41 | return log2Number(x);
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42 | } else {
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43 | // negative value -> complex value computation
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44 | return _log2Complex(new Complex(x, 0));
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45 | }
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46 | },
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47 | Complex: _log2Complex,
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48 | BigNumber: function BigNumber(x) {
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49 | if (!x.isNegative() || config.predictable) {
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50 | return x.log(2);
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51 | } else {
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52 | // downgrade to number, return Complex valued result
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53 | return _log2Complex(new Complex(x.toNumber(), 0));
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54 | }
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55 | },
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56 | 'Array | Matrix': function ArrayMatrix(x) {
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57 | return deepMap(x, this);
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58 | }
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59 | });
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60 | /**
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61 | * Calculate log2 for a complex value
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62 | * @param {Complex} x
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63 | * @returns {Complex}
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64 | * @private
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65 | */
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66 |
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67 | function _log2Complex(x) {
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68 | var newX = Math.sqrt(x.re * x.re + x.im * x.im);
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69 | 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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70 | }
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71 | }); |
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