error using plot vectors must be the same length

Why i am getting this error in plot (Data, hx,) and how to fix it?

This is my code

for i=2:test_points
  x_rec(i)=c1+c2*x_rec(i-1)+c3*hx(i-1)+c4*x_rec(i-1)*hx(i-1)+c5*x_rec(i-1)^2+c6*hx(i-1)^2+c7*x_rec(i-1)^2*hx(i-1)^2;
  hx(i)=d1+d2*x_rec(i-1)+d3*hx(i-1)+d4*x_rec(i-1)*hx(i-1)+d5*x_rec(i-1)^2+d6*hx(i-1)^2+d7*x_rec(i-1)^2*hx(i-1)^2;
  x_real(i)=x(start_point+i-1);
  error=error+(x_rec(i)-x_real(i))^2;
  DN=DN+x_real(i)^2;
end
Error_x(count)=sqrt(error)/sqrt(DN);
end
figure
hold on
plot (Data,Error_x,'s-r')
plot (Data,hx,'s-b')

This is the error

Vectors must be the same length.
Error in PE_HT (line 136)
plot (Data,hx,'s-b')

[dpb]

Too much undefined in the code snippet for us to tell...

[KSSV]

The error is clear....diemnsions of Data and hx are not same. Check their sizes.

Answer 1

[Asad (Mehrzad) Khoddam]

try to use this line of code inside the loop. For now, the code returns a single point for error;

for i=2:test_points
  x_rec(i)=c1+c2*x_rec(i-1)+c3*hx(i-1)+c4*x_rec(i-1)*hx(i-1)+c5*x_rec(i-1)^2+c6*hx(i-1)^2+c7*x_rec(i-1)^2*hx(i-1)^2;
  hx(i)=d1+d2*x_rec(i-1)+d3*hx(i-1)+d4*x_rec(i-1)*hx(i-1)+d5*x_rec(i-1)^2+d6*hx(i-1)^2+d7*x_rec(i-1)^2*hx(i-1)^2;
  x_real(i)=x(start_point+i-1);
  error=error+(x_rec(i)-x_real(i))^2;
  DN=DN+x_real(i)^2;
  Error_x(i)=sqrt(error)/sqrt(DN);
end

end