neizod/LICENSE.txt

## README.md

      
    Raw
  

              README.md
            
          
    Area of a Triangle

83b. Find area between 3 points which form a triangle.
How to use

Invoke function using 3 arguments of pair of coordination.
Nth arg (array) .... pair of coordination e.g. [1, 2]

Concept

from original triangle pqr:
. p                           ^
  ^ ***___                    |
    ^     ***___              | p[1]-r[1]
      ^         ***___    r   |
        ^         s ._____.   v
          ^         |    /    ^
            ^       |   /     |
              ^     |  /      | b
                ^   | /       |
                  ^ |/        |
                    . q       v
<------------------> <---->
     q[0]-p[0]         a

cut form p to s, and transform it into this:
. p               p".         ^
                    | \       |
                    |  \      | p[1]-r[1]
 p'               s |   \ r   |
.___________________._____.   v
^                   |    /    ^
    ^               |   /     |
        ^           |  /      | b
            ^       | /       |
                ^   |/        |
                    . q       v
<------------------> <---->
     q[0]-p[0]         a

now, there are three triangle (qsr, qsp', rsp"); or, for this hack, two triangle (large: rqp', small: rsp"), which calculate much easier!
Credit

@maettig 95b -> 93b -> 83b

  
## annotated.js
function(
        p,      // 1st coordinate pair
        q,      // 2nd
        r       // 3rd
) {
    return Math.abs(        // make sure the final area is positive
            (q[0]-p[0]) * (r[1]-q[1]) +   // square area of the large one
            (r[0]-q[0]) * (p[1]-q[1])     // square area of the small one
        )/2                 // turn those square area into triangle area
}

## index.js
function(p,q,r){return Math.abs((q[0]-p[0])*(r[1]-q[1])+(r[0]-q[0])*(p[1]-q[1]))/2}

## LICENSE.txt
            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
                    Version 2, December 2004

 Copyright (C) 2012 Nattawut Phetmak <neizod@gmail.com>

 Everyone is permitted to copy and distribute verbatim or modified
 copies of this license document, and changing it is allowed as long
 as the name is changed.

            DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. You just DO WHAT THE FUCK YOU WANT TO.

## package.json
{
  "name": "areaTriangle",

  "description": "this will calculate the area of triangle.",

  "keywords": [
    "area",
    "triangle",
    "math"
  ]
}

## test.html
<!DOCTYPE html>
<title>Area of a Triangle</title>
<div>Expected value: <b>2.5, 3, 0</b></div>
<div>Actual value: <b id="ret"></b></div>
<script>
  // write a small example that shows off the API for your example
  // and tests it in one fell swoop.

  var tri_area = function(p,q,r){return Math.abs((q[0]-p[0])*(r[1]-q[1])+(r[0]-q[0])*(p[1]-q[1]))/2}

  document.getElementById( "ret" ).innerHTML = [tri_area([1,3],[0,0],[2,1]),
                                                tri_area([4,7],[6,3],[4,4]),
                                                tri_area([1,1],[4,4],[9,9])];
</script>
	function(
	p, // 1st coordinate pair
	q, // 2nd
	r // 3rd
	) {
	return Math.abs( // make sure the final area is positive
	(q[0]-p[0]) * (r[1]-q[1]) + // square area of the large one
	(r[0]-q[0]) * (p[1]-q[1]) // square area of the small one
	)/2 // turn those square area into triangle area
	}
	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	Version 2, December 2004

	Copyright (C) 2012 Nattawut Phetmak <neizod@gmail.com>

	Everyone is permitted to copy and distribute verbatim or modified
	copies of this license document, and changing it is allowed as long
	as the name is changed.

	DO WHAT THE FUCK YOU WANT TO PUBLIC LICENSE
	TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

	0. You just DO WHAT THE FUCK YOU WANT TO.
	{
	"name": "areaTriangle",

	"description": "this will calculate the area of triangle.",

	"keywords": [
	"area",
	"triangle",
	"math"
	]
	}
	<!DOCTYPE html>
	<title>Area of a Triangle</title>
	<div>Expected value: <b>2.5, 3, 0</b></div>
	<div>Actual value: <b id="ret"></b></div>
	<script>
	// write a small example that shows off the API for your example
	// and tests it in one fell swoop.

	var tri_area = function(p,q,r){return Math.abs((q[0]-p[0])(r[1]-q[1])+(r[0]-q[0])(p[1]-q[1]))/2}

	document.getElementById( "ret" ).innerHTML = [tri_area([1,3],[0,0],[2,1]),
	tri_area([4,7],[6,3],[4,4]),
	tri_area([1,1],[4,4],[9,9])];
	</script>