Difference between revisions of "Systems of differential equations"
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| Line 17: | Line 17: | ||
function doIt() { | function doIt() { | ||
| − | var | + | var txt1 = JXG.GeonextParser.geonext2JS(document.getElementById("odeinput1").value); |
| − | f = new Function("x", "yy", "var | + | var txt2 = JXG.GeonextParser.geonext2JS(document.getElementById("odeinput2").value); |
| + | f = new Function("x", "yy", "var y1 = yy[0], y1 = yy[1]; var z1 = " + txt1 + "; var z2 = " + txt2 + "; return [z1,z2];"); | ||
brd.update(); | brd.update(); | ||
} | } | ||
function ode() { | function ode() { | ||
| − | return JXG.Math.Numerics.rungeKutta(JXG.Math.Numerics.predefinedButcher.Heun, [P1.Y()], [P1.X(), P1.X()+N.Value()], 200, f); | + | return JXG.Math.Numerics.rungeKutta(JXG.Math.Numerics.predefinedButcher.Heun, [P1.Y(),P2.Y()], [P1.X(), P1.X()+N.Value()], 200, f); |
} | } | ||
| − | var | + | var g1 = brd.createElement('curve', [[0],[0]], {strokeColor:'red', strokeWidth:'2px'}); |
| − | + | var g2 = brd.createElement('curve', [[0],[0]], {strokeColor:'black', strokeWidth:'2px'}); | |
| + | g1.updateDataArray = function() { | ||
var data = ode(); | var data = ode(); | ||
var h = N.Value()/200; | var h = N.Value()/200; | ||
| Line 35: | Line 37: | ||
this.dataX[i] = P1.X()+i*h; | this.dataX[i] = P1.X()+i*h; | ||
this.dataY[i] = data[i][0]; | this.dataY[i] = data[i][0]; | ||
| + | } | ||
| + | }; | ||
| + | g2.updateDataArray = function() { | ||
| + | var data = ode(); | ||
| + | var h = N.Value()/200; | ||
| + | this.dataX = []; | ||
| + | this.dataY = []; | ||
| + | for(var i=0; i<data.length; i++) { | ||
| + | this.dataX[i] = P2.X()+i*h; | ||
| + | this.dataY[i] = data[i][1]; | ||
} | } | ||
}; | }; | ||
doIt(); | doIt(); | ||
</jsxgraph> | </jsxgraph> | ||
Revision as of 10:50, 21 July 2010
Display solutions of the ordinary differential equation
- [math] y_1'= f_1(x,y_1,y_2)[/math]
- [math] y_2'= f_2(x,y_1,y_2)[/math]
with initial values [math](x_0,y_1)[/math], [math](x_0,y_2)[/math].
