求模r和主辐角θ（与规定有关,设-π＜θ≤π）z=x+yi=r*e^(iθ)=r(cosθ+iSinθ)r=|z|=(x^2+y^2)^(1/2)θ=arctan(y/x) x＞0,θ=-π +arctan(y/x) x＜0,y＜0θ=π +arctan(y/x) x＜0,y＞0x=0,y＞0时 θ=π/2x=0,y＜0...