matlab题目求解答

建立M文件： %由于解析解ode45只能求一阶的微分方程,所以必须先降阶,令y(1)=y;y(2)=y'
ff=[1-t^2/(2*pi)-y(1);y(2)];%则原方程变成方程组y(1)'=y(2);y(2)'=1-t^2/(2*pi)-y(1)
%解析解
t0=0;
tf=3*pi;
[t,y]=ode45('ww',[t0,tf],[0,0]);
plot(t,y,'r')
%数值解
y=dsolve('2*pi*D2y+2*pi*y-2*pi+t^2','t');
t=0:0。01:3*pi;
hold on;
plot(t,eval(y)) %eval(y)将符号变量y变成数值y