159 lines
2.3 KiB
Markdown
159 lines
2.3 KiB
Markdown
---
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title: "math"
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description: "Trigonometry, logarithms, and roots"
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weight: 70
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type: "docs"
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---
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ƿit provides three math modules with identical functions but different angle representations:
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```javascript
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var math = use('math/radians') // angles in radians
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var math = use('math/degrees') // angles in degrees
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var math = use('math/cycles') // angles in cycles (0-1)
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```
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## Trigonometry
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### sine(angle)
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```javascript
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math.sine(math.pi / 2) // 1 (radians)
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math.sine(90) // 1 (degrees)
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math.sine(0.25) // 1 (cycles)
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```
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### cosine(angle)
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```javascript
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math.cosine(0) // 1
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```
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### tangent(angle)
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```javascript
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math.tangent(math.pi / 4) // 1 (radians)
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```
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### arc_sine(n)
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Inverse sine.
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```javascript
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math.arc_sine(1) // pi/2 (radians)
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```
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### arc_cosine(n)
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Inverse cosine.
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```javascript
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math.arc_cosine(0) // pi/2 (radians)
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```
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### arc_tangent(n, denominator)
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Inverse tangent. With two arguments, computes atan2.
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```javascript
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math.arc_tangent(1) // pi/4 (radians)
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math.arc_tangent(1, 1) // pi/4 (radians)
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math.arc_tangent(-1, -1) // -3pi/4 (radians)
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```
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## Exponentials and Logarithms
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### e(power)
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Euler's number raised to a power. Default power is 1.
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```javascript
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math.e() // 2.718281828...
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math.e(2) // e^2
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```
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### ln(n)
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Natural logarithm (base e).
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```javascript
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math.ln(math.e()) // 1
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```
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### log(n)
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Base 10 logarithm.
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```javascript
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math.log(100) // 2
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```
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### log2(n)
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Base 2 logarithm.
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```javascript
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math.log2(8) // 3
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```
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## Powers and Roots
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### power(base, exponent)
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```javascript
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math.power(2, 10) // 1024
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```
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### sqrt(n)
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Square root.
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```javascript
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math.sqrt(16) // 4
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```
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### root(radicand, n)
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Nth root.
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```javascript
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math.root(27, 3) // 3 (cube root)
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```
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## Constants
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Available in the radians module:
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```javascript
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math.pi // 3.14159...
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math.e() // 2.71828...
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```
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## Example
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```javascript
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var math = use('math/radians')
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// Distance between two points
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var distance = function(x1, y1, x2, y2) {
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var dx = x2 - x1
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var dy = y2 - y1
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return math.sqrt(dx * dx + dy * dy)
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}
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// Angle between two points
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var angle = function(x1, y1, x2, y2) {
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return math.arc_tangent(y2 - y1, x2 - x1)
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}
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// Rotate a point
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var rotate = function(x, y, a) {
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var c = math.cosine(a)
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var s = math.sine(a)
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return {
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x: x * c - y * s,
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y: x * s + y * c
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}
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}
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```
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