Lines will not plot

Good Afternoon

I am trying to plot multiple lines on a plot but, nothing is showing up. The variables are full of data, i have no clue where to go from here.

for L = [3 4 6] % m
    if L == 3
        w=1;
    elseif L == 4
        w=2;
    elseif L == 6
        w=3;
    end
    
    for i = 1 : 3
        
        if i == 1
            D(w,i) = 20 .* 10 .^ (-3); % m
        elseif i == 2
            D(w,i) = 30 .* 10 .^ (-3); % m
        elseif i == 3
            D(w,i) = 40 .* 10 .^ (-3); % m
        end
        
        for j = 1 : 3
            
            if j == 1
                T_inf(w,i,j) = 523.15;
                sp_o(w,i,j) = sp_1;
                k_o(w,i,j) = k_1;
                Pr_o(w,i,j) = Pr_1;
            elseif j == 2
                T_inf(w,i,j) = 648.15;
                sp_o(w,i,j) = sp_1;
                k_o(w,i,j) = k_1;
                Pr_o(w,i,j) = Pr_1;
            elseif j == 3
                T_inf(w,i,j) = 773.15;
                sp_o(w,i,j) = sp_3;
                k_o(w,i,j) = k_3;
                Pr_o(w,i,j) = Pr_3;
            end
                            %inside stuff
                Re_Di(w,i,j) = 4 .* mf ./ ( pi .* D(w,i) .* mu );
                NuDi_bar(w,i,j) = 0.023 .* Re_Di(w,i,j) .^ 0.8 .* Pr .^ 0.4 ;
                hi_bar(w,i,j) = NuDi_bar(w,i,j) .* k_i ./ D(w,i) ;
            
            figure(w)
            for k = 1 : 1: 21
                V(w,i,j,k) = k + 19;
                Tm_i(w,i,j,k) = T_mi;
                T_inf(w,i,j,k) = T_inf(w,i,j);
                hi_bar(w,i,j,k) = hi_bar(w,i,j);
                
                %outside stuff
                Re_Do(w,i,j,k) = V(w,i,j,k) .* D(w,i) ./ sp_o(w,i,j) ;
                NuDo_bar(w,i,j,k) = 0.3 + (0.62 .* Re_Do(w,i,j,k) .^ (1 ./ 2) .* Pr_o(w,i,j) .^ (1 ./ 3)) .* (1 + (Re_Do(w,i,j,k) ./ 282000) .^ (5 ./ 8)) .^ (4 ./ 5) ./ ((1 + (0.4 ./ Pr_o(w,i,j)) .^ (2 ./ 3)) .^ (1 ./4));
                ho_bar(w,i,j,k) = NuDo_bar(w,i,j,k) .* k_o(w,i,j) ./ D(w,i);
                
                %Finding which one is closest to Tm,o
                U_bar(w,i,j,k) = ((1 ./ hi_bar(w,i,j,k)) + (1 ./ ho_bar(w,i,j,k))) .^ (-1);
                e(w,i,j,k) = exp(-((pi .* D(w,i) .* L) ./ (mf .* cp)) .* U_bar(w,i,j,k));
                T(w,i,j,k) = T_inf(w,i,j,k) - Tm_i(w,i,j,k);
                Ti(w,i,j,k) = e(w,i,j,k) .* T(w,i,j,k);
                Tm_o(w,i,j,k) = T_inf(w,i,j) - Ti(w,i,j,k);
                
                
                %plot(V(w,i),Tm_o(w,i,j),'DisplayName',['D : ' num2str(D(w,i)) ' mm, T_inf : ' num2str(T_inf(w,i,j)) ' K'])
                
%                 if (T_mo - 0.1 < Tm_o(w,i,j,k)) && (T_mo + 0.1 > Tm_o(w,i,j,k))
%                     T_inf(w,i,j,k)
%                     Tm_o(w,i,j,k)
%                     V(w,i,j,k)
%                     D(w,i)
%                     L
%                       
%                 end
            end
            
            plot(V(w,i,j),Tm_o(w,i,j))
            fprintf('%d\n',Tm_o(w,i,j));

        end
        
    end
    
    %figure(w)
    %plot(V(w,i,j,k),Tm_o(w,i,j,k)),
    xlabel('Velocity(m/s)'), ylabel('Temp(k)'),
    title(['Tmo vs. Velocity ', num2str(L),' m'])
    
    hold on
    
 
end

Answer 1

[Star Strider]

You appear to be plotting points.

You need to call hold before the outermost loop:

figure
hold all
for L = [3 4 6] % m

then plot with a marker:

plot(V(w,i,j),Tm_o(w,i,j),'pg')

since the plot function plots lines between two points, in order of their appearance. If you are plotting fewer than two points at a time, you need to use a marker to see them.

Then call hold again after the end of the outermost loop:

end
hold off

to keep from plotting more points to the same axes.