# Plot 2D Gaussian spot and histograms of horizontal and vertical axis in one figure

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Floris Wulf on 18 Mar 2021
Edited: Rohit Pappu on 22 Mar 2021
I am simulating a spot of a Gaussian laser beam. I've added my simple code below. It creates three figures: one plot of the Gaussian spot itself, and two plots of the histograms of the vertical coordinates and horizontal coordinates. What I would like to do is create one figure with these three plots, with the histograms along their corresponding axes. I've added an example of this below that I created by combining the figures in MS Paint.
I would like to create this picture in MATLAB instead, does anyone know if this is possible? If yes, how?
% Parameters of the Gaussian beam
M2 = 1.45; % M-squared, beam propagation factor
lambda = 800E-9; % Wavelength of the light [m]
w_init = 0.010; % Initial beam waist before the mirror [m]
sigma_pos = w_init/2; % Standard deviation of the initial Gaussian position distribution [m]
% Generating the random positions of 10000 light rays according to a
% Gaussian distribution
Nrays = 10000; % Number of rays
sigma_posy = sigma_pos/sqrt(2);
sigma_posz = sigma_posy;
qy0 = normrnd(0, sigma_posy, 1, Nrays);
qz0 = normrnd(0, sigma_posz, 1, Nrays);
% Plotting spot
figure()
box on
plot(qz0, qy0, 'b.')
xlabel('z [m]')
ylabel('y [m]')
axis square
%% Histogram plot
figure()
box on
histfit(sqrt(2)*qz0)
xlim([-0.015 0.015])
ylabel('Intensity')
figure()
box on
histfit(sqrt(2)*qy0)
xlim([-0.015 0.015])
ylabel('Intensity') Rohit Pappu on 22 Mar 2021
The above diagram can be created using subplot (for creating the grid of plots) and camroll (for rotating the histogram)
% Create a 3x3 subplot
% Z intensities
subplot(3,3,[1,2]);
box on
h1 = histfit(sqrt(2)*qz0)
xlim([-0.015 0.015])
ylabel('Intensity')
ax1 = h1.Parent;
set(ax1, 'xticklabel' ,[]);
% Plotting spot
subplot(3,3,[4 5 7 8]);
box on
f = plot(qz0, qy0, 'b.')
xlabel('z [m]')
ylabel('y [m]')
axis square
% Y intensities
subplot(3,3,[6 9])
box on
h2 = histfit(sqrt(2)*qy0)
xlim([-0.015 0.015])
ylabel('Intensity')
ax2 = h2.Parent;
camroll(ax2,-90) % Rotate the plot clockwise by 90 degrees
set(ax2, 'XTickLabel',[]);
Floris Wulf on 22 Mar 2021
Ah OK, that explains it. I will use your proposed workaround, and I'll accept your answer. Thank you very much for your help.

R2019b

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