设 I＝ 泊松积分 ＝ (0,∝ )∫[e^(-x^2)] dx I^2 = {(0,∝ )∫[e^(x^2)] dx }*{(0,∝ )∫[e^(y^2)] dy= (积分区间D )∫∫[e^(-x^2 - y^2 )] dxdy (面积分）=> [ 积分变换 ρ^2 = x^2 + y^2 ,dxdy = ρdρdθ ,D:0 ≤...�ø��ӣ���ֻҪһ����ʽ���ɻ�� = (�̦�)/2