Why is my plot not showing anything?

for ii=1:n \n

    if x(ii)<=a 
        v=((-q*b*x(ii)^2)/(12*E*I))*(3*L+3*a-2*x(ii));
        vi=((-q*b*x)/(2*E*I)).*(L+a-x);
    else
        v=((-q)/(24*E*I))*(x(ii)^4-4*L*x(ii)^3+6*L.^2*x(ii)^2-4*a.^3*x(ii)+a.^4);
        vi=((-q)/(6*E*I))*(x(ii)^3-3*L*x(ii)^2+3*L.^2*x(ii)-a.^3);
    end
end

subplot(2,1,1); plot(x,v);

title(' ');

subplot(2,1,2); plot(x,vi);

Should there be a 'hold on' somewhere in the code? Thanks

[Stephen23]

It is possible that a loop is not required anyway. Please tell us what size the variables are: q, E, I, x, L, etc.

Answer 1

[madhan ravi]

for ii=1:n    %EDITED

      if x(ii)<=a 
          v(ii)=((-q*b*x(ii)^2)/(12*E*I))*(3*L+3*a-2*x(ii));
          vi(ii)=((-q*b*x)/(2*E*I)).*(L+a-x);
      else
          v(ii)=((-q)/(24*E*I))*(x(ii)^4-4*L*x(ii)^3+6*L.^2*x(ii)^2-4*a.^3*x(ii)+a.^4);
          vi(ii)=((-q)/(6*E*I))*(x(ii)^3-3*L*x(ii)^2+3*L.^2*x(ii)-a.^3);
      end
  end

    plot(x(1:numel(v)),v);

    hold on

    plot(x(1:numel(vi)),vi);

[madhan ravi]

The hold on is only required if and obligations you want to put multiple graphs in one plot. (ii) is included next to the variables in order to prevent t overwriting. At the beginning of the loop you put n/n where it should be n otherwise the loop is useless only calculating for the first iteration.

[Jacqueline Hoang]

Yes, I am trying to graph 2 figures, v(ii) and vi(ii) stacked on top of each other.

[madhan ravi]

So use hold on , if it worked make sure to accept the answer so that people know the question is solved.

[madhan ravi]

Else let know what’s additionally required