%clc
clear all
close all
v = 1:20
v(1:2:20) = -1
v(2:2:20) = 10:-1:1
v(17:end) = []
v1 = v(1:4)
v2 = v(5:8)
v3 = v(9:12)
v4 = v(13:16)
A = [v1; v2; v3; v4]
B = [v1' v2' v3' v4']
C = A
C(1, :) = []
C(:, 1) = []
% or C = A(2:end, 2:end)

D = B
D(end, :) = []
D(:, end) = []
% or D = C(1:3, 1:3)

E = C + D'

I = [-6 6];
figure
subplot(1, 2, 1)
f = @(x) sqrt(abs(x)).*cos(x);
fplot(f, I)
xlabel('x')
ylabel('y')
subplot(1, 2, 2)
g = @(x) x.^2./exp(x);
fplot(g, I)
xlabel('x')
ylabel('y')
F = f(D) + g(E)'