>> a=magic(3)a =8 1 63 5 74 9 2>> b=zeros(size(a));for i=1:size(a,1)for j=1:size(a,2)if a(i,j)>5b(i,j)=5;%%a中大于5的数全部换成5elseb(i,j)=4;%%小于5的数全部换成4endendendbb =5 4 54 4 54 5 4...