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Algorithm to calculate the Arithmetic Geometric Mean #897

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Merged
raklaptudirm merged 14 commits into from
Feb 24, 2022
Merged

Algorithm to calculate the Arithmetic Geometric Mean #897

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dd9481e
Create ArithmeticGeometricMean.js
Rudxain Feb 20, 2022
2cf398a
Merge branch 'TheAlgorithms:master' into patch-1
Rudxain Feb 23, 2022
6ab3f4b
Finally added the test script for AGM
Rudxain Feb 23, 2022
6ab7a98
Better doc, and corrected some formatting
Rudxain Feb 23, 2022
df68055
Merge branch 'TheAlgorithms:master' into patch-1
Rudxain Feb 23, 2022
1dca4e6
Fixed syntax typos
Rudxain Feb 23, 2022
f1382e3
Added more tests and made FP comparison more "loose"
Rudxain Feb 23, 2022
1762ac9
Patched bugs
Rudxain Feb 23, 2022
0b812e9
Fixed-0 bug
Rudxain Feb 23, 2022
3c8e162
Again, tried to fix minus zero
Rudxain Feb 23, 2022
f9d28a8
Finally fixed all bugs (probably)
Rudxain Feb 23, 2022
f81549d
Fixed style (probably)
Rudxain Feb 23, 2022
b0b0776
Fixed style
Rudxain Feb 23, 2022
4f7431c
Fixed all style
Rudxain Feb 23, 2022
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24 changes: 24 additions & 0 deletions Maths/ArithmeticGeometricMean.js
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/**
* @function agm
* @description This finds the Arithmetic-Geometric Mean between any 2 numbers.
* @param {Number} a - 1st number, also used to store Arithmetic Mean.
* @param {Number} g - 2nd number, also used to store Geometric Mean.
* @return {Number} - AGM of both numbers.
* @see [AGM](https://en.wikipedia.org/wiki/Arithmetic%E2%80%93geometric_mean)
*/

export const agm = (a, g) => {
if (a === g) return a; //avoid rounding errors, and increase efficiency
let x; //temp var, for detecting rounding differences between `sqrt` and division
do {
[a, g, x] = [(a + g) / 2, Math.sqrt(a * g), a]
} while (a !== x && !isNaN(a));
/*
`x !== a` ensures the return value has full precision,
and prevents infinite loops caused by rounding errors (no need for "epsilon").
Precision is not the same as accuracy, but they're related.
This function isn't always 100% accurate (round-errors), but at least is more than 95% accurate.
`!isNaN(x)` prevents infinite loops caused by invalid inputs like: negatives, NaNs and both Infinities.
*/
return a
}