MATLAB编写一个m文件,画出下列分段函数所表示的曲面

用MATLAB，编写一个m文件并画出下列分段函数所表示的曲面

x=-1:0.1:1;
y=-1:0.1:1;
[X,Y]=meshgrid(x,y);
xsize = size(x,2);
ysize = size(y,2);
z=zeros(xsize,ysize);
for i=1:1:xsize
    for j=1:1:ysize
        xtemp = x(i);
        ytemp = y(i);
        if(xtemp+ytemp>1)
            z(i,j)= 0.54*exp(-0.75*xtemp*xtemp-3.75*ytemp*ytemp-1.5*ytemp);
        else if(xtemp+ytemp>-1 && xtemp+ytemp<=1)
                z(i,j)=0.7575*exp(-xtemp*xtemp-6*ytemp*ytemp);
            else if(xtemp+ytemp<=-1)
                    z(i,j)=0.5457*exp(-0.75*xtemp*xtemp-3.75*ytemp*ytemp+1.5*ytemp);
                end
            end
        end
        
    end
end

surf(x,y,z);