ERROR

clear, clc, close all;
syms x
n=11;
f(x)=cos(pi*x/2);
[v]=VECTORFV(n,f);
p=1;
for j=1:3:n
    p=p*v(j);
end
s1=0;
for k=2:3:n
    s1=s1+(v(k));
end
s2=0;
for k=3:3:n
    s2=s2+(v(k));
end
s=s1-s2;

z=p-s;
disp(z)
b=0;
for k=3:3:n
    b=b+((((k-n/2)^(k/3))/(factorial(k/3))*v(k)));
end
g(x)=eval(f(n/2))+b;

fplot(f,[(n/2)-1,(n/2)+1], Color= 'r')
hold on
fplot(g,[(n/2)-1,(n/2)+1], Color= 'b')







function[v]= VECTORFV(n,f)
syms x
v=zeros(n,1);
for k=1:3:n
    a=((-1)^k)/(k*(k+1)*(k+2));
    b=eval(int(f^k,x,0,n));
    v(k)=a*b;
end
for k=2:3:n
    a=((-1)^(k+1))/(k^3-k);
    b=eval(int(f,x,0,k));
    v(k)=a*b^n;
end
faux(x)=f(x);
for k=3:3:n
    fa=diff(faux,x,k/3);
    v(k)=eval(fa(n/2));
    faux(x)=f(x);
end
end