设u=e^y
du=e^ydy=udy, dy=du/u
代入原方程
du/udx=u
du/u^2=dx
两边积分:-1/u=x+C
-1/e^y=x+C
y=-in(-x+C1)
在matlab里输入y=dsolve('Dy=exp(y),'x')即可
>> dsolve('Dy=exp(y)','x')
ans =
log(-1/(x+C1))
分离变量
dy/dx=e^y
e^(-y)dy=dx
e^(-y)d(-y)=-dx
e^(-y)=-x+c
-y=ln(c-x)
y=-ln(c-x)