Random walks: Difference between revisions

From JSXGraph Wiki
m (Undo revision 3145 by Annie (Talk), Reason: Spam)
 
No edit summary
 
(One intermediate revision by one other user not shown)
Line 36: Line 36:


<jsxgraph width="600" height="600">
<jsxgraph width="600" height="600">
var brd = JXG.JSXGraph.initBoard('jxgbox', {originX: 300, originY: 300, unitX: 3, unitY: 3});
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-100, 100, 100, -100]});
var t = brd.createElement('turtle');
var t = brd.create('turtle');


function run() {
function run() {
Line 44: Line 44:
   t.hideTurtle();
   t.hideTurtle();
   brd.suspendUpdate();
   brd.suspendUpdate();
   var nr = $('number').value*1;
   var nr = document.getElementById('number').value*1;
   for (i=0;i<nr;i++) {
   for (i=0;i<nr;i++) {
     t.setPenColor(JXG.hsv2rgb(Math.round(Math.random()*255),Math.random(),Math.random()));
     t.setPenColor(JXG.hsv2rgb(Math.round(Math.random()*255),Math.random(),Math.random()));
Line 56: Line 56:
     t.home();
     t.home();
   }
   }
   $('output').value = (sumdist/nr).toFixed(3);
   document.getElementById('output').value = (sumdist/nr).toFixed(3);
   brd.unsuspendUpdate();
   brd.unsuspendUpdate();
}
}
Line 65: Line 65:


===Source code===
===Source code===
<source lang="html4strict">
<source lang="javascript">
<jsxgraph width="600" height="600">
var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-100, 100, 100, -100]});
var brd = JXG.JSXGraph.initBoard('jxgbox', {originX: 300, originY: 300, unitX: 3, unitY: 3});
var t = brd.create('turtle');
var t = brd.createElement('turtle');


function run() {
function run() {
Line 74: Line 73:
   var stepSize = 5;  
   var stepSize = 5;  
   brd.suspendUpdate();
   brd.suspendUpdate();
   var nr = $('number').value*1;
   var nr = document.getElementById('number').value*1;
   for (i=0;i<nr;i++) {
   for (i=0;i<nr;i++) {
     t.setPenColor(JXG.hsv2rgb(Math.round(Math.random()*255),Math.random(),Math.random()));
     t.setPenColor(JXG.hsv2rgb(Math.round(Math.random()*255),Math.random(),Math.random()));
Line 86: Line 85:
     t.home();
     t.home();
   }
   }
   $('output').value = (sumdist/nr).toFixed(3);
   document.getElementById('output').value = (sumdist/nr).toFixed(3);
   brd.unsuspendUpdate();
   brd.unsuspendUpdate();
}
}
Line 92: Line 91:
   t.cs();
   t.cs();
}
}
</jsxgraph>
</source>
</source>



Latest revision as of 12:19, 8 June 2011

Number of random walks:

Fixed values in this simulation are:

  • stepsize [math]\displaystyle{ {}=5 }[/math] and
  • Number of steps per walk [math]\displaystyle{ {}= 100 }[/math].

Therefore, the expected squared distance from the starting point will be equal to

  • [math]\displaystyle{ 100\cdot 5^2=2500 }[/math].

Average square of the distance between starting point and endpoint of the walks:

Source code

var brd = JXG.JSXGraph.initBoard('jxgbox', {boundingbox: [-100, 100, 100, -100]});
var t = brd.create('turtle');

function run() {
  var i,j,dist,sumdist=0.0;
  var stepSize = 5; 
  brd.suspendUpdate();
  var nr = document.getElementById('number').value*1;
  for (i=0;i<nr;i++) {
     t.setPenColor(JXG.hsv2rgb(Math.round(Math.random()*255),Math.random(),Math.random()));
     for (j=0;j<100;j++) {
        var a = Math.floor(360*Math.random()); 
        t.right(a); 
        t.forward(stepSize);
     }
     dist = t.pos[0]*t.pos[0]+t.pos[1]*t.pos[1];
     sumdist += dist;
     t.home();
  }
  document.getElementById('output').value = (sumdist/nr).toFixed(3);
  brd.unsuspendUpdate();
}
function clearturtle() {
  t.cs();
}

External links