User:Wogga62/Sandbox
From Wikipedia, the free encyclopedia
The Math object is always available. (Note that it is an object, not a constructor like Array or Date.) It has a number of Properties which return useful constants and also a number of Methods which provide access to mathematical functions such as Cosine and Square Root. All the trigonometric functions use angles expressed in radians; not degrees or grads. (One Radian is about 57.296°.)
| Property | Value Returned rounded to 5 digits | Description |
|---|---|---|
| Math.E | 2.7183 | Euler's constant, also known as e |
| Math.LN2 | 0.69315 | Natural logarithm of 2 |
| Math.LN10 | 2.3026 | Natural logarithm of 10 |
| Math.LOG2E | 1.4427 | Logarithm to the base 2 of e |
| Math.LOG10E | 0.43429 | Logarithm to the base 10 of e |
| Math.PI | 3.1416 | π : circumference/diameter of a circle |
| Math.SQRT1_2 | 0.70711 | Square root of a half |
| Math.SQRT2 | 1.4142 | Square root of 2 |
| Example | Value Returned rounded to 5 digits | Description |
|---|---|---|
| Math.abs(-2.3) | 2.3 | Absolute value : (x < 0) ? -x : x |
| Math.acos(Math.SQRT1_2) | 0.78540 rad. = 45° | Arc Cosine |
| Math.asin(Math.SQRT1_2) | 0.78540 rad. = 45° | Arc Sine |
| Math.atan(1) | 0.78540 rad. = 45° | Half Circle Arc Tangent. -Pi/2 to +Pi/2 |
| Math.atan2(-3.7, -3.7) | -2.3562 rad. = -135° | Whole Circle Arc Tangent. -Pi to +Pi |
| Math.ceil(1.1) | 2 | Ceiling : next integer >= argument |
| Math.cos(Math.PI/4) | 0.70711 | Cosine trigonometric function : rad. input |
| Math.exp(1) | 2.7183 | Exponential Function : e raised to this power |
| Math.floor(1.9) | 1 | Floor : next integer <= argument |
| Math.log(Math.E) | 1 | Natural Logarithm, base e |
| Math.max(1, -2) | 1 | Maximum : (x > y) ? x : y |
| Math.min(1, -2) | -2 | Minimum : (x < y) ? x : y |
| Math.pow(-3, 2) | 9 | To the power of : Math.pow(x, y) gives xy |
| Math.random() | 0.17068 | Random number from 0 to 1 |
| Math.round(1.5) | 2 | Round to the nearest counting number |
| Math.sin(Math.PI/4) | 0.70711 | Sine trigonometric function : rad. input |
| Math.sqrt(49) | 7 | Square Root |
| Math.tan(Math.PI/4) | 1 | Tangent trigonometric function : rad. input |
There are one or two other Methods available in some recent software. See http://www.w3schools.com/jsref/jsref_obj_math.asp
Example of uses of the Math object
where = ( a*Math.sin(ang) + b*Math.cos(ang) > Math.sqrt(r2) ) ? "outside" : "inside"