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859cfa208a
* Fix #1902: typo in an example in the documentation * Replace recursive calls in typed-functions with `this`-style calls * Replace more recursive calls in typed-functions with `this`-style calls * Refactor compareNatural to use this-style recursion Co-authored-by: josdejong <wjosdejong@gmail.com>
76 lines
2.2 KiB
JavaScript
76 lines
2.2 KiB
JavaScript
import { factory } from '../../utils/factory'
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import { deepMap } from '../../utils/collection'
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import { logNumber } from '../../plain/number'
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const name = 'log'
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const dependencies = ['config', 'typed', 'divideScalar', 'Complex']
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export const createLog = /* #__PURE__ */ factory(name, dependencies, ({ typed, config, divideScalar, Complex }) => {
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/**
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* Calculate the logarithm of a value.
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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.log(x)
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* math.log(x, base)
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*
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* Examples:
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*
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* math.log(3.5) // returns 1.252762968495368
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* math.exp(math.log(2.4)) // returns 2.4
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*
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* math.pow(10, 4) // returns 10000
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* math.log(10000, 10) // returns 4
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* math.log(10000) / math.log(10) // returns 4
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*
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* math.log(1024, 2) // returns 10
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* math.pow(2, 10) // returns 1024
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*
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* See also:
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*
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* exp, log2, log10, log1p
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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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* @param {number | BigNumber | Complex} [base=e]
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* Optional base for the logarithm. If not provided, the natural
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* logarithm of `x` is calculated.
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* @return {number | BigNumber | Complex | Array | Matrix}
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* Returns the logarithm of `x`
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*/
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return typed(name, {
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number: function (x) {
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if (x >= 0 || config.predictable) {
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return logNumber(x)
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} else {
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// negative value -> complex value computation
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return new Complex(x, 0).log()
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}
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},
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Complex: function (x) {
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return x.log()
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},
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BigNumber: function (x) {
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if (!x.isNegative() || config.predictable) {
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return x.ln()
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} else {
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// downgrade to number, return Complex valued result
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return new Complex(x.toNumber(), 0).log()
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}
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},
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'Array | Matrix': function (x) {
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return deepMap(x, this)
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},
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'any, any': function (x, base) {
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// calculate logarithm for a specified base, log(x, base)
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return divideScalar(this(x), this(base))
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}
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})
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})
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