请教几道简单的MATLAB程序设计题目

A = pascal(7) %生成7*7 pascal矩阵

B = A([1,3,5],[5,6,7]) %构成矩阵B

C = A(5:7,1:3)%构成矩阵C

D = B-1*C

A =

1 1 1 1 1 1 1

1 2 3 4 5 6 7

1 3 610152128

1 41020355684

1 5153570 126 210

1 62156 126 252 462

1 72884 210 462 924

B =

1 1 1

152128

70 126 210

C =

1 515

1 621

1 728

D =

0-4 -14

1415 7

69 119 182

第二题：

function A=prime_number()

N=100

j=1

for i=2:N

if prod(rem(i,2:(i-1)))~=0

A(j)=i

j=j+1

end

end

A =

2 3 5 7111317192329313741434753596167717379838997

syms x y

y1=cos(x1).^0.5

y2=(x^2)/4+(y^2)/16

subplot(2,2,2)

plot(x1,y1)

subplot(2,2,3)

ezsurf(y2,[-2,2,-4,4])