cactus

Thanks for the help on my previous question.

I set up my dataset as follows:

points := [[2.612499, 16.24096], [3.437499, 14.21687], [3.437498, 11.22891], [3.437497, 8.192769], [4.262499, 6.361444], [5.224999, 7.662649], [7.974999, 7.51807], [10.175, 8.192769], [10.725, 9.59036], [12.375, 8.289155], [14.1625, 8.626504], [16.0875, 8.578312], [17.7375, 7.469878], [19.9375, 7.469878], [21.5875, 7.469878], [22.6875, 7.180721], [23.65, 8.289155], [24.0625, 9.638553...

I tried pairs of x and y:

> with(CurveFitting);

> points:=[[2.612499,16.24096]],[3.437499,14.21687],[3.437499,11.22891],[3.437499,8.192769],[4.262499,6.361444],[5.224999,7.662649]];

> h := PolynomialInterpolation(points, x);

I got

Error, (in CurveFitting:-PolynomialInterpolation) data points not in recognizable format

I also tried

> points := [0, 1], [1, 2], [3, -7], [4, -3];
    ...

How do I plot the numeric solution for both x(t) and y(t) on one graph to the differential system:

x'(t) = 2*x(t)-x(t)*y(t),   y'(t) = -y(t) + 0.4*x(t)*y(t)

x(0) = 5 and y(0) = 1

Thanks

<img alt="" src="file:///C:/DOCUME%7E1/raccach/LOCALS%7E1/Temp/moz-screenshot.png" /><img alt="" src="file:///C:/DOCUME%7E1/raccach/LOCALS%7E1/Temp/moz-screenshot-1.png" /><img alt="" src="file:///C:/DOCUME%7E1/raccach/LOCALS%7E1/Temp/moz-screenshot-2.png" /><img alt="" src="file:///C:/DOCUME%7E1/raccach/LOCALS%7E1/Temp/moz-screenshot-3.png" /><br />
<br />

Please Ignore the previous posting, I had a few mistakes.

I have the following terms: >

a := .178131; 0.178131 >

b := -0.6814e-1*`if`(t = 0, 6, `if`(t = 1, 10, `if`(t = 2, 15, `if`(t = 3, 20, NULL))));

 c := 0.16242e-1*`if`(t = 0, 6, `if`(t = 1, 10, `if`(t = 2, 15, `if`(t = 3, 20, NULL))))^1.5;

The ODE is:

I have the following terms: >

a := .178131; 0.178131 >

e := -0.6814e-1*`if`(t = 0, 6, `if`(t = 1, 10, `if`(t = 2, 15, `if`(t = 3, 20, NULL))));

 f := 0.16242e-1*`if`(t = 0, 6, `if`(t = 1, 10, `if`(t = 2, 15, `if`(t = 3, 20, NULL))))^1.5;

The ODE is: