Difference between revisions of "Parabola"

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That means the numbers below ''a'', ''b'', and ''c'' are updated if the points ''A'', ''B'', and ''C'' are dragged. And other way round,
 
That means the numbers below ''a'', ''b'', and ''c'' are updated if the points ''A'', ''B'', and ''C'' are dragged. And other way round,
 
these numbers are editable.
 
these numbers are editable.
 +
 +
See [Slider and function plot] for an easier example howto plot a parabola.
 +
 
<jsxgraph box="box2" width="600" height="400">
 
<jsxgraph box="box2" width="600" height="400">
 
hook = true;
 
hook = true;

Revision as of 16:11, 15 January 2021

This is an example for JSXGraph with two boards and so called hooks into HTML. That means the numbers below a, b, and c are updated if the points A, B, and C are dragged. And other way round, these numbers are editable.

See [Slider and function plot] for an easier example howto plot a parabola.

a b c

The underlying JavaScript code

<div id="box2" class='jxgbox' style="width:375px; height:150px;"></div>

<table style="border: 0px solid black; text-align: center" width="500px">
<tr>
  <th style="border: 1px solid black" width="100px">a</th>
  <th style="border: 1px solid black" width="100px">b</th>
  <th style="border: 1px solid black" width="100px">c</th>
</tr>
<tr>
  <td><input type="text" id="print_a" size="2" maxlength="7" 
    style="border:none; text-align:right; font-size:1.2em; "
    onKeyUp="board2.select('A').moveTo([parseFloat(this.value),0]); board2.update(); board.update();" onfocus="hook=false;" onblur="hook=true"
  ></td>
  <td><input type="text" id="print_b" size="2" maxlength="7" 
    style="border:none; text-align:right; font-size:1.2em; "
    onKeyUp="board2.select('B').moveTo([parseFloat(this.value),0]); board2.update(); board.update();" onfocus="hook=false;" onblur="hook=true"
  ></td>
  <td><input type="text" id="print_c" size="2" maxlength="7" 
    style="border:none; text-align:right; font-size:1.2em; "
    onKeyUp="board2.select('C').moveTo([parseFloat(this.value),0]); board2.update(); board.update();" onfocus="hook=false;" onblur="hook=true"
  ></td>
</tr>
</table>  

<div id="box" class="jxgbox" style="width:600px; height:400px;"></div>
hook = true;
board2 = JXG.JSXGraph.loadBoardFromString('box2', 'eNrtmm1v2zYQgD/bv4JAPteS7D...Y6tu7MXarPHfJ+R+tkHyx', 'Geonext');

var board = JXG.JSXGraph.initBoard('box', {boundingbox: [-5, 5, 7, -3], axis: true});

var curve = board.create('functiongraph', [function(t){ 
        return board2.select('A').X() * t * t + board2.select('B').X() * t + board2.select('C').X(); 
    }, -10, 10]);						
			
function print_table() {
  if (hook){
    document.getElementById('print_a').value = board2.select('A').X().toFixed(2);
    document.getElementById('print_b').value = board2.select('B').X().toFixed(2);
    document.getElementById('print_c').value = board2.select('C').X().toFixed(2);
  }
};

board2.addChild(board);
			
print_table_id = board2.on('update', print_table);

GEONExT Construction used in this example

Sliders.gxt