matlab4阶龙格库塔法程序.doc

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1、functionvarargout=saxplaxliu(varargin)clc,clearx0=0;xn=1.2;y0=1;h=0.1;[y,x]=lgkt4j(x0,xn,y0,h);n=length(x);fprintf('i  x(i)  y(i)');fori=1:n   fprintf('%2d%4.4f%4.4f',i,x(i),y(i));endfunctionz=f(x,y)  z=-2*x*y^2;function[y,x]=lgkt4j(x0,xn,y0,h)x=x0:h:xn;n=length(x);y1=x

2、;y1(1)=y0;fori=1:n-1   K1=f(x(i),y1(i));   K2=f(x(i)+h/2,y1(i)+h/2*K1);   K3=f(x(i)+h/2,y1(i)+h/2*K2);   K4=f(x(i)+h,y1(i)+h*K3);   y1(i+1)=y1(i)+h/6*(K1+2*K2+2*K3+K4);end  y=y1;  结果：i  x(i)  y(i)10.00001.000020.10000.990130.20000.961540.30000.917450.40000.862160.50000.8000

3、70.60000.735380.70000.671190.80000.6098100.90000.5525111.00000.5000121.10000.4525131.20000.4098