function e=trapezhiba(x,y); 
s=trapez(x,y)
n=length(x)-1
u=zeros(1,n/2+1)
for i=1:n/2+1
    u(i)=x(2*i-1)
end
v=zeros(1,n/2+1)
for i=1:n/2+1
    v(i)=y(2*i-1)
end
t=trapez(u,v)
e=abs(t-s)