Add a red line on the graph

My current code is:

num_simulations = 10000;

%Common parameters
Discount_Rate_min = 0.06;       % assume 6-8%
Discount_Rate_max = 0.08;
Discount_Rate_values = unifrnd(Discount_Rate_min, Discount_Rate_max, [num_simulations, 1]);

Lifetime = 20;    % years

Electricity_Cost_values = 0.063;      %EUR/kWh

FLH = 7134;

LHV = 33.33;    %kWh/kgH2

%SOEC parameters
CAPEX_System_SOEC_mean = 1800;     %$/kW
CAPEX_System_SOEC_std = 816.5;
CAPEX_System_SOEC_values = normrnd(CAPEX_System_SOEC_mean, CAPEX_System_SOEC_std, [num_simulations,1]);
CAPEX_System_SOEC_values(CAPEX_System_SOEC_values < 800) = 800;
CAPEX_System_SOEC_values(CAPEX_System_SOEC_values > 2800) = 2800;

%CAPEX_Stack_SOEC_values = 0.5*CAPEX_System_SOEC_values;    % 50% of CAPEX system 

CAPEX_SOEC_values = CAPEX_System_SOEC_values;

OPEX_SOEC_values = 3;   % 3% of CAPEX/a

System_Efficiency_SOEC_mean = 0.805;
System_Efficiency_SOEC_std = 0.0286;
System_Efficiency_SOEC_values = normrnd(System_Efficiency_SOEC_mean, System_Efficiency_SOEC_std, [num_simulations,1]);
System_Efficiency_SOEC_values(System_Efficiency_SOEC_values < 0.77) = 0.77;
System_Efficiency_SOEC_values(System_Efficiency_SOEC_values > 0.84) = 0.84;


%PEM parameters
CAPEX_System_PEM_mean = 1075;      %$/kW
CAPEX_System_PEM_std = 347.01;
CAPEX_System_PEM_values = normrnd(CAPEX_System_PEM_mean, CAPEX_System_PEM_std, [num_simulations,1]);
CAPEX_System_PEM_values(CAPEX_System_PEM_values < 650) = 650;
CAPEX_System_PEM_values(CAPEX_System_PEM_values > 1500) = 1500;

%CAPEX_Stack_PEM_values = 0.35*CAPEX_System_PEM_values;    % 35% of CAPEX system

CAPEX_PEM_values = CAPEX_System_PEM_values;

OPEX_PEM_values = 3;

System_Efficiency_PEM_mean = 0.655;
System_Efficiency_PEM_std = 0.0204;
System_Efficiency_PEM_values = normrnd(System_Efficiency_PEM_mean, System_Efficiency_PEM_std, [num_simulations,1]);
System_Efficiency_PEM_values(System_Efficiency_PEM_values < 0.63) = 0.63;
System_Efficiency_PEM_values(System_Efficiency_PEM_values > 0.68) = 0.68;


%AEC parameters
CAPEX_System_AEC_mean = 625;     % $/kW
CAPEX_System_AEC_std = 183.71;
CAPEX_System_AEC_values = normrnd(CAPEX_System_AEC_mean, CAPEX_System_AEC_std, [num_simulations,1]);
CAPEX_System_AEC_values(CAPEX_System_AEC_values < 400) = 400;
CAPEX_System_AEC_values(CAPEX_System_AEC_values > 850) = 850;

%CAPEX_Stack_AEC_values = 0.35*CAPEX_System_AEC_values;     % 35% of CAPEX system

CAPEX_AEC_values = CAPEX_System_AEC_values;

OPEX_AEC_values = 3;

System_Efficiency_AEC_mean = 0.68;
System_Efficiency_AEC_std = 0.0245;
System_Efficiency_AEC_values = normrnd(System_Efficiency_AEC_mean, System_Efficiency_AEC_std, [num_simulations,1]);
System_Efficiency_AEC_values(System_Efficiency_AEC_values < 0.65) = 0.65;
System_Efficiency_AEC_values(System_Efficiency_AEC_values > 0.71) = 0.71;

% Calculate SOEC LCOH values
term1_S = LHV ./ System_Efficiency_SOEC_values;
term2_S = Discount_Rate_values .* (1 + Discount_Rate_values).^Lifetime;
term3_S = (OPEX_SOEC_values / 100);
term4_S = CAPEX_SOEC_values ./ FLH;
LCOH_SOEC = term1_S .* ((term2_S ./ ((1 + Discount_Rate_values).^Lifetime - 1) + term3_S) .* term4_S + Electricity_Cost_values);


% Calculate PEM LCOH values
term1_P = LHV ./ System_Efficiency_PEM_values;
term2_P = Discount_Rate_values .* (1 + Discount_Rate_values).^Lifetime;
term3_P = (OPEX_PEM_values / 100);
term4_P = CAPEX_PEM_values ./ FLH;
LCOH_PEM = term1_P .* ((term2_P ./ ((1 + Discount_Rate_values).^Lifetime - 1) + term3_P) .* term4_P + Electricity_Cost_values);


% Calculate AEC LCOH values
term1_A = LHV ./ System_Efficiency_AEC_values;
term2_A = Discount_Rate_values .* (1 + Discount_Rate_values).^Lifetime;
term3_A = (OPEX_AEC_values / 100);
term4_A = CAPEX_AEC_values ./ FLH;
LCOH_AEC = term1_A .* ((term2_A ./ ((1 + Discount_Rate_values).^Lifetime - 1) + term3_A) .* term4_A + Electricity_Cost_values);

% Create histograms for SOEC, AEC, and PEM LCOH values
figure;

% SOEC LCOH
subplot(3, 1, 1);
histogram(LCOH_SOEC, 'Normalization', 'probability', 'EdgeColor', 'w');
Ax1 = gca;
[dRL{1},dBE{1},dBC{1},dBD{1}] = drawRedLine(Ax1);
xlabel('LCOH (per kWh)');
ylabel('Probability');
title('SOEC LCOH');
ylim([0, 0.1]);
% AEC LCOH
subplot(3, 1, 2);
histogram(LCOH_AEC, 'Normalization', 'probability', 'EdgeColor', 'w');
Ax2 = gca;
[dRL{2},dBE{2},dBC{2},dBD{2}] = drawRedLine(Ax2);
xlabel('LCOH (per kWh)');
ylabel('Probability');
title('AEC LCOH');
ylim([0, 0.1]);
% PEM LCOH
subplot(3, 1, 3);
histogram(LCOH_PEM, 'Normalization', 'probability', 'EdgeColor', 'w');
Ax3 = gca;
[dRL{3},dBE{3},dBC{3},dBD{3}] = drawRedLine(Ax3);
xlabel('LCOH (per kWh)');
ylabel('Probability');
title('PEM LCOH');
ylim([0, 0.1]);
% Adjust layout
sgtitle('Monte Carlo Simulation Results for SOEC, AEC, and PEM');
% Show the plot


% Adjust layout
sgtitle('Monte Carlo Simulation Results for SOEC, AEC, and PEM');
% Show the plot

% function drawRedLine(axh)
% %   Draws the red line in each histogram subplot.
%     H = axh.Children;
%     BinCtrs = H.BinEdges(1:end-1)+diff(H.BinEdges)/2;
%     B = polyfit(BinCtrs,H.Values,2) ;
%     RedLine = polyval(B, BinCtrs);
%     FudgeFactor = max(H.Values) - max(RedLine);
%     hold on
%     plot(axh,BinCtrs, RedLine  + FudgeFactor,  '-r', 'LineWidth',1)
%     hold off
% end

DN = ["SOEC LCOH" "AEC LCOH" "PEM LCOH"];
figure
hold on
for k = 1:3
    hb = bar(dBC{k}, dBD{k}, 'DisplayName',[DN(k)+" Histogram"], 'FaceAlpha',0.5);
    % plot(BE{k}, RL{k}, 'LineWidth',3, 'DisplayName',[DN(k)+" Distribution"], 'Color','r')
    plot(dBE{k}, dRL{k}, 'LineWidth',3, 'DisplayName',[DN(k)+" Distribution"], 'Color',hb.FaceColor)
end
hold off
grid
xlabel('LCOH [€/kgH2]');
ylabel('Probability');
title('Sweden in 2030 7134h')
legend('Location','northoutside')

function [dRL,dBE,dBC,dBD] = drawRedLine(axh)                           % MODIFIED: Add Outputs
%   Draws the red line in each histogram subplot.
H = axh.Children;
BinCtrs = H.BinEdges(1:end-1)+diff(H.BinEdges)/2;
Data = H.Values;
u = mean(BinCtrs);
s = std(Data);
ndpdf = @(b,x) b(1) .* exp(-(x-b(2)).^2 ./ b(3));
B = fminsearch(@(b)norm(Data-ndpdf(b,BinCtrs)), [max(H.Values); u; s]);
% text(axh, B(2), max(H.Values), sprintf('$p(x) = %.3fe^{-\\frac{(%.2f-x)^2}{%.3f}}$', B), 'Horiz','center','Vert','bottom','Interpreter','latex')
RedLine = ndpdf(B, H.BinEdges);
hold on
plot(axh,H.BinEdges, RedLine,  '-r', 'LineWidth',1.5)
hold off
dRL = RedLine;
dBE = H.BinEdges;
dBC = BinCtrs;
dBD = Data;
end


In this code, I would like to add a red line with fixed values like the below graph.
%fixed value parameter
CAPEX_System_values = 800;
System_Efficiency_values = 0.83;
OPEX_System_values = 3;

% Calculate fixed LCOH values
term1_F = 40;
term2_F = Discount_Rate_values .* (1 + Discount_Rate_values).^Lifetime;
term3_F = (OPEX_System_values / 100);
term4_F = CAPEX_System_values ./ FLH;
LCOH_F = term1_F .* ((term2_F ./ ((1 + Discount_Rate_values).^Lifetime - 1) + term3_F) .* term4_F + Electricity_Cost_values);

[Image Analyst]

Not sure what you mean. Simply use

hold on;
plot(x, y, 'r-', 'LineWidth', 2);

with the proper x and y and it should work. You've already plotted 4 lines on the bar chart so you should know how to do it.

Answer 1

[Noah Prisament]

For future reference, code is more readable if you format it in a "code block" in the question editor. Also please give a more detailed question in the future as you currently only shared your existing code.

It looks like you are looking to plot a vertical line in your figure. to do so you can use the xline function.

It also looks like you currently have some "add red line" functions in this code that take an axes handle and add a red line, so you should be able to call these functions with the axes handles you already have such as "Ax1" to add red lines to those subplots.

Answer 2

[Aquatris]

If you want to put a vertical line on an x value, you can also use

plot(0:0.01:2*pi,sin(0:0.01:2*pi)) % random plot
xline(3,'r') % vertical x line, there is also a yline() which is horizontal