1 |
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2 |
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3 | const number = require('../../utils/number')
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4 | const deepMap = require('../../utils/collection/deepMap')
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5 |
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6 | function factory (type, config, load, typed) {
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7 | /**
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8 | * Compute the sign of a value. The sign of a value x is:
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9 | *
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10 | * - 1 when x > 0
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11 | * - -1 when x < 0
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12 | * - 0 when x == 0
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13 | *
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14 | * For matrices, the function is evaluated element wise.
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15 | *
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16 | * Syntax:
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17 | *
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18 | * math.sign(x)
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19 | *
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20 | * Examples:
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21 | *
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22 | * math.sign(3.5) // returns 1
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23 | * math.sign(-4.2) // returns -1
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24 | * math.sign(0) // returns 0
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25 | *
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26 | * math.sign([3, 5, -2, 0, 2]) // returns [1, 1, -1, 0, 1]
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27 | *
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28 | * See also:
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29 | *
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30 | * abs
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31 | *
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32 | * @param {number | BigNumber | Fraction | Complex | Array | Matrix | Unit} x
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33 | * The number for which to determine the sign
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34 | * @return {number | BigNumber | Fraction | Complex | Array | Matrix | Unit}e
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35 | * The sign of `x`
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36 | */
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37 | const sign = typed('sign', {
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38 | 'number': number.sign,
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39 |
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40 | 'Complex': function (x) {
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41 | return x.sign()
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42 | },
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43 |
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44 | 'BigNumber': function (x) {
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45 | return new type.BigNumber(x.cmp(0))
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46 | },
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47 |
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48 | 'Fraction': function (x) {
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49 | return new type.Fraction(x.s, 1)
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50 | },
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51 |
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52 | 'Array | Matrix': function (x) {
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53 | // deep map collection, skip zeros since sign(0) = 0
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54 | return deepMap(x, sign, true)
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55 | },
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56 |
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57 | 'Unit': function (x) {
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58 | return sign(x.value)
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59 | }
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60 | })
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61 |
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62 | sign.toTex = { 1: `\\mathrm{\${name}}\\left(\${args[0]}\\right)` }
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63 |
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64 | return sign
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65 | }
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66 |
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67 | exports.name = 'sign'
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68 | exports.factory = factory
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