37 lines
977 B
Markdown
37 lines
977 B
Markdown
---
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title: vectorAngle
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tags: math,beginner
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---
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Returns the angle (theta) value between two vectors.
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Use `Math.trunc()` to pick the integer value of length. Use `slice()` slice the incoming array into individual vectors.
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Use `forEach()`, `Math.pow()` and `Math.sqrt()` to iterate over the vectors and calculate the magnitude of each vector and the scalar product.
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Use `Math.acos()` to calculate arccos and get the theta.
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```js
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const theta = ((...x) =>{
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let half = Math.trunc(x.length / 2);
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let a = x.slice(0 , half);
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let b = x.slice(half);
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let magnitudeOfA = 0;
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a.forEach((a) => magnitudeOfA += Math.pow(a , 2));
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magnitudeOfA = Math.sqrt(magnitudeOfA);
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let magnitudeOfB = 0;
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b.forEach((b) => magnitudeOfB += Math.pow(b , 2));
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magnitudeOfB = Math.sqrt(magnitudeOfB);
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let scalar = 0;
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a.forEach((a , i) => scalar += a * b[i]);
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return Math.acos(scalar / (magnitudeOfA*magnitudeOfB));
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});
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```
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```js
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theta(3,4,4,3); // 0.283794109208328
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```
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