Difference between revisions of "Lagrange interpolation (dup)"

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Line 36: Line 36:
  
 
         function addPoint() {
 
         function addPoint() {
           p.push(board.createElement('point',[(Math.random()-0.5)*10,(Math.random()-0.5)*10],{style:6}));
+
           p.push(board.createElement('point',[(Math.random()-0.5)*10,(Math.random()-0.5)*3],{style:6}));
 
           board.update();
 
           board.update();
 
         }
 
         }
Line 52: Line 52:
 
         p[0] = board.createElement('point', [-1,2], {style:6});
 
         p[0] = board.createElement('point', [-1,2], {style:6});
 
         p[1] = board.createElement('point', [0,-3], {style:6});
 
         p[1] = board.createElement('point', [0,-3], {style:6});
        p[2] = board.createElement('point', [1,4], {style:6});
 
        p[3] = board.createElement('point', [2,1], {style:6});
 
 
          
 
          
 
         var polynomial = function(x) {
 
         var polynomial = function(x) {
 
                 var y = 0.0;
 
                 var y = 0.0;
                 for (var i=0;i<4;i++) {
+
                 for (var i=0;i<p.length;i++) {
 
                   var t = p[i].Y();
 
                   var t = p[i].Y();
                   for (var k=0;k<4;k++) {
+
                   for (var k=0;k<p.length;k++) {
 
                     if (k!=i) {
 
                     if (k!=i) {
 
                       t *= (x-p[k].X())/(p[i].X()-p[k].X());
 
                       t *= (x-p[k].X())/(p[i].X()-p[k].X());
Line 69: Line 67:
 
             };
 
             };
 
         graph = board.createElement('curve', ['x', polynomial, 'x', -10, 10], {curveType:'graph'});
 
         graph = board.createElement('curve', ['x', polynomial, 'x', -10, 10], {curveType:'graph'});
 +
 +
        function addPoint() {
 +
          p.push(board.createElement('point',[(Math.random()-0.5)*10,(Math.random()-0.5)*3],{style:6}));
 +
          board.update();
 +
        }
 +
 
</source>
 
</source>
  
  
 
[[Category:Examples]]
 
[[Category:Examples]]

Revision as of 18:22, 3 December 2008

Constructs a polynomial of degree n through n+1 given points. Points can be added by clicking on "Add point".

        board = JXG.JSXGraph.initBoard('box', {originX: 250, originY: 250, unitX: 50, unitY: 25});
        // Axes
        b1axisx = board.createElement('axis', [[0,0], [1,0]], {});
        b1axisy = board.createElement('axis', [[0,0], [0,1]], {});

        var p = [];
        p[0] = board.createElement('point', [-1,2], {style:6});
        p[1] = board.createElement('point', [0,-3], {style:6});
        
        var polynomial = function(x) {
                var y = 0.0;
                for (var i=0;i<p.length;i++) {
                  var t = p[i].Y();
                  for (var k=0;k<p.length;k++) {
                    if (k!=i) {
                      t *= (x-p[k].X())/(p[i].X()-p[k].X());
                    }
                  }
                  y += t;
                }
                return y;
            };
        graph = board.createElement('curve', ['x', polynomial, 'x', -10, 10], {curveType:'graph'});

        function addPoint() {
          p.push(board.createElement('point',[(Math.random()-0.5)*10,(Math.random()-0.5)*3],{style:6}));
          board.update();
        }