%第一题的主程序,ti1st.m
[t,Y] = ode45(@kalmon1,[0 1],[0 0 -1])
%把自变量取区间[0,1]。delta_x的初值直接取成了0,不知道是否合理
plot(t,Y,'r--')
%第一题的函数文件 kalmon1.m
function dy = kalmon1(t,y)
%y(1)即delta_x,y(2)即P,y(3)即x
dy = zeros(3,1);    % a column vector
q=0.5;
r=0.6;
dy(1) = -y(1)+3*(5-6*exp(-t))^2*y(2)*(-3*(5-6*exp(-t))^2*y(1))/r; %在这行的-3*(5-6*exp(-t))^2*y(1)前面加上delta_z(t)的表达式即可
dy(2) = -2*y(2)-9*(5-6*exp(-t))^4*y(2)^2/r+q;
dy(3) = 5-6*exp(-t)+y(1);