littlechild

为啥我想解一个函数的解析解
y=dsolve('Dx=-(0.5*(((x^2+y^2))^(1/2))-x)/y','x(-100)=0','y')

它答案里怎么有个 _Z

y =

RootOf(100*_Z+100*(_Z^2+y^2)^(1/2)+(-100)^(1/2)*10000^(1/2)*y^(1/2))

_Z是是指啥啊