www.gusucode.com > 司守奎《Lingo软件及应用习题解答》的源程序 > 司守奎《Lingo软件及应用习题解答》的源程序/《Lingo软件及应用习题解答》程序和数据/12第12章/Lt12_10_11.m

    clc, clear
syms x1(t) y1(t) a0 a b k12 N a x2(t) y2(t) x3(t) y3(t) T
[x1,y1]=dsolve(diff(x1)==-a*x1,diff(y1)==k12*x1-b*y1,...
    x1(0)==N*a0,y1(0)==0);
x1=simplify(x1)
y1=simplify(y1), pretty(y1)
[x2,y2]=dsolve(diff(x2)==-a*x2,diff(y2)==k12*x2-b*y2,...
    x2(0)==subs(x1,t,T)+N*a0,y2(0)==subs(y1,t,T));
x2=simplify(x2)
y2=simplify(y2), pretty(y2)
[x3,y3]=dsolve(diff(x3)==-a*x3,diff(y3)==k12*x3-b*y3,...
    x3(0)==subs(x2,t,T)+N*a0,y3(0)==subs(y2,t,T));
x3=simplify(x3)
y3=simplify(y3), pretty(y3)