Clear[f, x, y]
f[x_, y_] = Piecewise[{{(1 - x^2 - y^2)^6.5, 0 <= x^2 + y^2 <= 1}, {Exp[-6.4 (x^2 + y^2)], 1 <= x^2 + y^2}}]
Plot3D[f[x, y], {x, -1, 1}, {y, -1, 1}, PlotRange -> All]
对了,顺便,能不能别再在标题里加“大神”之类的词了啊,看着超烦燥的知不知道。