Legend doesn't have colors

I'm trying to make a plot that has mutliple lines, and the plot works fine and each line is a different color, but the legend does not showing which value goes with which line. Any help on this would be appreciated. Here is my code and the plot:

clc; clear;
%
% Given:
% Surface
L = 4/1000;                 % thickness of the glass, m
k = 1.4;                    % thermal conductivity of glass, W/m-K
T_si = 15;                  % inner surface temperature, oC
%
% Air inside
T_inf_i = 25;               % air temperature ouside, oC
hi = 10;                    % convection heat trasnfer coefficient, W/m^2-K
%
% Air outside
T_inf_o = -10;              % air temperature inside, oC
ho = 65;                    % convection heat trasnfer coefficient, W/m^2-K
% 
% Calculate thermal resistances
R_conv_i = 1/hi;            % inside convection resistance
R_cond = L/k;               % conduction resistance
%
% Variables
ho_values = [2 20 65 100];
T_inf_o_range = -30:1:30; 
%
% Initialize matrix to store power requirements
power_req = zeros(length(ho_values), length(T_inf_o_range));
%
% Loop over h_o values
for i = 1:length(ho_values)
    ho = ho_values(i);
    %
    % Calculate outside convection resistance
    R_conv_o = 1/ho;
    %
    % Loop over T_inf_o values
    for j = 1:length(T_inf_o_range)
        T_inf_o = T_inf_o_range(j);
        
        % Calculate total thermal resistance
        R_total = R_conv_i + R_cond + R_conv_o;
        
        % Calculate heat flux
        q = (T_si - T_inf_o) / R_total;
        
        % Store power requirement
        power_req(i, j) = q;
    end
end
%  
% Plot power requirement as a function of T_inf_o for each h_o
hold on
for i = 1:length(ho_values)
    plot(T_inf_o_range, power_req(i, :))
end
xlabel('T_{\infty, o} (^oC)')
ylabel('Power Requirement (W/m^2)')
legend('ho = 2', 'ho = 20', 'ho = 65', 'ho = 100')
hold off

[the cyclist]

I've formatted and run your code here. I don't quite understand the problem you are describing.

[Mitchell Terry]

on my end, the legend doesn't have any color. Is there a possible setting I need to change?

[Walter Roberson]

When we run the code here, legend() has color.

[Mitchell Terry]

Mine doesn't though

Answer 1

[Mitchell Terry]

Hello, I have figured it out, it was because my linewidth was too small. Thank you for your help!

[the cyclist]

Glad you figured it out.

[Adam Danz]

What was your linewidth values? If the lines appeared in the axes, they should have appeared in the legend.