c22.m

matlab例程MATLAB 6.x版的内建数据类型（Built-in data type）就有5种以上

%(a) For  k = 3
y0=dsolve('D2y+4*Dy+3*y=0','y(0)=3','Dy(0)=-7','t')  
%(b) For k = 4
y0=dsolve('D2y+4*Dy+4*y=0','y(0)=3','Dy(0)=-7','t')  
%(c) For k = 40
y0=dsolve('D2y+4*Dy+40*y=0','y(0)=3','Dy(0)=-7','t')