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大小: 645KB文件類型: .rar金幣: 2下載: 0 次發布日期: 2021-06-04
- 語言: Matlab
- 標簽: 微分方程??Runge-Kutta??Matlab??
資源簡介
給出了四階Runge-Kutta法解常微分方程組的一般公式,并用此公式解了兩個實例:捕食者-被捕食者模型和Lorenz方程(蝴蝶效應),附有實驗報告和Matlab代碼

代碼片段和文件信息
function?Lorenz(X0Y0Z0hT)
%LORENZ?Summary?of?this?function?goes?here
%%初始值X0Y0Z0?步長h?積分區間長度T
%???Detailed?explanation?goes?here
format?long;
dxdt=inline(‘-10*x+10*y‘?‘x‘?‘y‘?‘z‘);
dydt=inline(‘28*x-y-x*z‘?‘x‘?‘y‘?‘z‘);
dzdt=inline(‘-8/3*z+x*y‘?‘x‘?‘y‘?‘z‘);
x0?=?[X0?Y0?Z0];
t?=?[0:h:T]‘;
x1?=?ones(T/h+13);
x1(1:)?=?x0;
x2?=?ones(T/h+13);
x2(1:)?=?x0;
f1?=?ones(T/h3);
f2?=?ones(T/h3);
f3?=?ones(T/h3);
f4?=?ones(T/h3);
for?i=1:T/h
????f1(i1)?=?feval(dxdtx1(i1)x1(i2)x1(i3));?
????f1(i2)?=?feval(dydtx1(i1)x1(i2)x1(i3));?
????f1(i3)?=?feval(dzdtx1(i1)x1(i2)x1(i3));
????f2(i1)?=?feval(dxdtx1(i1)+h/2*f1(i1)x1(i2)+h/2*f1(i2)x1(i3)+h/2*f1(i3));
????f2(i2)?=?feval(dydtx1(i1)+h/2*f1(i1)x1(i2)+h/2*f1(i2)x1(i3)+h/2*f1(i3));
????f2(i3)?=?feval(dzdtx1(i1)+h/2*f1(i1)x1(i2)+h/2*f1(i2)x1(i3)+h/2*f1(i3));
????f3(i1)?=?feval(dxdtx1(i1)+h/2*f2(i1)x1(i2)+h/2*f2(i2)x1(i3)+h/2*f2(i3));
????f3(i2)?=?feval(dydtx1(i1)+h/2*f2(i1)x1(i2)+h/2*f2(i2)x1(i3)+h/2*f2(i3));
????f3(i3)?=?feval(dzdtx1(i1)+h/2*f2(i1)x1(i2)+h/2*f2(i2)x1(i3)+h/2*f2(i3));
????f4(i1)?=?feval(dxdtx1(i1)+h*f3(i1)x1(i2)+h*f3(i2)x1(i3)+h*f3(i3));
????f4(i2)?=?feval(dydtx1(i1)+h*f3(i1)x1(i2)+h*f3(i2)x1(i3)+h*f3(i3));
????f4(i3)?=?feval(dzdtx1(i1)+h*f3(i1)x1(i2)+h*f3(i2)x1(i3)+h*f3(i3));
????x2(i+1:)?=?x1(i:)+h/6*(f1(i:)+2*f2(i:)+2*f3(i:)+f4(i:));
????x1(i+1:)?=?x2(i:);
end
fprintf(‘\n??????x??????????y?????????z?????????t???\n‘);
for?j=1:T/h+1
????fprintf(‘??%7.2f??%8.7f??%8.7f??%8.7f??\n‘t(j)x2(j1)x2(j2)x2(j3));
end
subplot(131);
plot(x2(1:1:T/h+11)x2(1:1:T/h+12)‘r‘);
title(‘x-y‘);
subplot(132)
plot(x2(1:1:T/h+11)x2(1:1:T/h+13)‘r‘);
title(‘x-z‘);
subplot(133)
plot(x2(1:1:T/h+12)x2(1:1:T/h+13)‘r‘);
title(‘y-z‘);
end
?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件?????863210??2011-11-30?21:29??四階Runge-Kutta法解常微分方程組\Ex1RK_公開版.pdf
?????文件???????1918??2011-11-25?17:05??四階Runge-Kutta法解常微分方程組\Lorenz.m
?????文件???????1361??2011-11-25?17:07??四階Runge-Kutta法解常微分方程組\ppm.m
?????目錄??????????0??2011-11-30?21:31??四階Runge-Kutta法解常微分方程組
-----------?---------??----------?-----??----
???????????????866489????????????????????4
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