A=magic(9)
B=A(1:2:end,:)
C=A(:,2:2:end)
B*C
K=[1,2,3;4,5,6;-7,0,-9]
p=[70;160;-170]
x=K\p
t=-2*pi:0.05:2*pi;
y=cos(t.^4).^3;
y2=sin(t);
plot(t,y,t,y2)