examp7_1.m

东北大学 薛定谔的高等应用数学问题MATLAB求解的源代码

syms t; u=exp(-5*t)*cos(2*t+1)+5;
uu=5*diff(u,t,2)+4*diff(u,t)+2*u

syms t y;
y=dsolve(['D4y+10*D3y+35*D2y+50*Dy+24*y=',...
    '87*exp(-5*t)*cos(2*t+1)+92*exp(-5*t)*sin(2*t+1)+10'])

y=dsolve(['D4y+10*D3y+35*D2y+50*Dy+24*y=',...
    '87*exp(-5*t)*cos(2*t+1)+92*exp(-5*t)*sin(2*t+1)+10'],'y(0)=3',...
    'Dy(0)=2','D2y(0)=0','D3y(0)=0')

[n,d]=rat(double(vpa(-445/26*cos(1)-51/13*sin(1)-69/2))); [n,d]

vpa(-445/26*cos(sym(1))-51/13*sin(1)-69/2+8704/185)

y=dsolve(['D4y+10*D3y+35*D2y+50*Dy+24*y=',...
    '87*exp(-5*t)*cos(2*t+1)+92*exp(-5*t)*sin(2*t+1)+10'],'y(0)=1/2',...
    'Dy(pi)=1','D2y(2*pi)=0','Dy(2*pi)=1/5')
vpa(y,10)