%  符號微分方程解 例題集
 dsolve('Dx = -a*x')% ans=
 x = dsolve('Dx = -a*x','x(0) = 1','s')
 y = dsolve('(Dy)^2 + y^2 = 1','y(0) = 0')
 S = dsolve('Df = f + g','Dg = -f + g','f(0) = 1','g(0) = 2')% S.f=,S.g=結構體    
 y= dsolve('Dy = y^2*(1-y)') % y的隱函數                   
 dsolve('Df = f + sin(t)', 'f(pi/2) = 0')
 dsolve('D2y = -a^2*y', 'y(0) = 1, Dy(pi/a) = 0')