8楼: Originally posted by alober at 2017-08-02 19:01:08
1=I = C\int_{-\infty}^{+\infty}\int_{-\infty}^{+\infty}\exp(-\alpha\sqrt{(x+by)^2+(\sqrt{1-b^2}y)^2})dxdy \mathop{=}^{x+by=m,\sqrt{1-b^2}y=n} \frac{C}{\sqrt{1-b^2}}\int_{-\infty}^{+\infty}\int_{-\in ...