Slider in Matlab code

MATLAB code is a basic interactive application for visualizing a stochastic process :

close all
clc

% Initialize figure
fig = figure('Position', [100, 100, 1000, 600], 'Name', 'Interactive Stochastic Fractional Order Analysis');

% Initial parameters
mu = 0.2;
sigma = 0.2;
s = 100;
dt = 0.01;
N = 1000;
T = N * dt;

% Create sliders and labels for adjusting parameters
uicontrol('Style', 'text', 'Position', [20, 550, 100, 20], 'String', '\mu');
uicontrol('Style', 'slider', 'Min', 0, 'Max', 1, 'Value', mu, 'Position', [120, 550, 300, 20], 'Callback', @(src, event) updatePlot());
 
uicontrol('Style', 'text', 'Position', [20, 500, 100, 20], 'String', '\sigma');
uicontrol('Style', 'slider', 'Min', 0, 'Max', 1, 'Value', sigma, 'Position', [120, 500, 300, 20], 'Callback', @(src, event) updatePlot());

uicontrol('Style', 'text', 'Position', [20, 450, 100, 20], 'String', 's');
uicontrol('Style', 'slider', 'Min', 100, 'Max', 500, 'Value', s, 'Position', [120, 450, 300, 20], 'Callback', @(src, event) updatePlot());

uicontrol('Style', 'text', 'Position', [20, 400, 100, 20], 'String', '\Delta t');
uicontrol('Style', 'slider', 'Min', 0.001, 'Max', 0.1, 'Value', dt, 'Position', [120, 400, 300, 20], 'Callback', @(src, event) updatePlot());

uicontrol('Style', 'text', 'Position', [20, 350, 100, 20], 'String', 'N_T');
uicontrol('Style', 'slider', 'Min', 100, 'Max', 2000, 'Value', N, 'Position', [120, 350, 300, 20], 'Callback', @(src, event) updatePlot());

% Create axes for plotting
ax = axes('Parent', fig, 'Position', [0.1, 0.1, 0.8, 0.4]);

% Initial plot
 set(findobj('String', '\sigma'), 'Value', sigma);  % Update the slider value
 set(findobj('String', '\mu'), 'Value', mu);  % Update the slider value
 set(findobj('String', '\Delta t'), 'Value', dt);  % Update the slider value
 set(findobj('String', 's'), 'Value', s);  % Update the slider value
  set(findobj('String', 'N_T'), 'Value', N);  % Update the slider value

updatePlot();  % Manually call the updatePlot function

% Update plot function
function updatePlot()
     
    % Get current slider values
    mu = get(findobj('String', '\mu'), 'Value');
    sigma = get(findobj('String', '\sigma'), 'Value');
    s = get(findobj('String', 's'), 'Value');
    dt = get(findobj('String', '\Delta t'), 'Value');
    N = get(findobj('String', 'N_T'), 'Value');
    
     
    % Run stochastic simulation with updated parameters
    alpha = simulateStochasticProcess(mu, sigma, dt, N);
    
    % Define time vector based on the simulation duration
    T = N * dt;
    t = dt:dt:T;
    
    % Update plot based on simulation results
    ax = findobj(gcf, 'Type', 'axes');
    plot(ax, t, alpha, 'LineWidth', 1);
    xlabel('Time t');
    ylabel('Stochastic   Order \alpha');
    title(['\mu = ', num2str(mu), ', \sigma = ', num2str(sigma), ', s = ', num2str(s), ', \Delta t = ', num2str(dt), ', N_T = ', num2str(N)]);
    grid on;
    
    % Update slider values to reflect the changes
    set(findobj('String', '\mu'), 'Value', mu);
    set(findobj('String', '\sigma'), 'Value', sigma);
    set(findobj('String', 's'), 'Value', s);
    set(findobj('String', '\Delta t'), 'Value', dt);
    set(findobj('String', 'N_T'), 'Value', N);
end

% Function to simulate stochastic process
function alpha = simulateStochasticProcess(mu, sigma, dt, N)
    sd = sqrt(dt);
    dB = sd * randn(1, N);
    B = cumsum(dB);
    alpha = mu + sigma * B;
end

I try to display Slider Values when i change these values and visualize the effect on the stochastic process, also each slider shows a corresponding LaTeX text.

how can I do? thanks.

Answer 1

[Voss]

The labels (i.e., the 'text'-stlye uicontrols) have the strings you are passing to findobj, not the sliders, so findobj returns those text uicontrols, not the slider uicontrols.

In fact, it is not usually necessary to use findobj. Instead, store the uicontrol handles in variables, and refer to those variables later when you want to get properties of the uicontrols. To access those variables in uicontrol callbacks, there are various approaches you can take; I like to have the callbacks nested in a main function, like in the code that follows.

I've included updating the labels' Strings to reflect the current slider Values in updatePlot (which I guess is what you were going for when you were updating the slider Values). LaTeX in a uicontrol text String will not be rendered, but you can use uilabels instead of uicontrols to do it.

GUI() % run the main function


function GUI() % your script is now a function with the other functions nested in it

% Initialize figure
fig = figure('Position', [100, 100, 1000, 600], 'Name', 'Interactive Stochastic Fractional Order Analysis');

% Initial parameters
mu = 0.2;
sigma = 0.2;
s = 100;
dt = 0.01;
N = 1000;
T = N * dt;

% Create sliders and labels for adjusting parameters
h_labels = [ ...
    uicontrol('Style', 'text', 'Position', [20, 550, 100, 20]) ...
    uicontrol('Style', 'text', 'Position', [20, 500, 100, 20]) ...
    uicontrol('Style', 'text', 'Position', [20, 450, 100, 20]) ...
    uicontrol('Style', 'text', 'Position', [20, 400, 100, 20]) ...
    uicontrol('Style', 'text', 'Position', [20, 350, 100, 20]) ...
    ];
h_sliders = [ ...
    uicontrol('Style', 'slider', 'Min', 0, 'Max', 1, 'Value', mu, 'Position', [120, 550, 300, 20], 'Callback', @(src, event) updatePlot()) ...
    uicontrol('Style', 'slider', 'Min', 0, 'Max', 1, 'Value', sigma, 'Position', [120, 500, 300, 20], 'Callback', @(src, event) updatePlot()) ...
    uicontrol('Style', 'slider', 'Min', 100, 'Max', 500, 'Value', s, 'Position', [120, 450, 300, 20], 'Callback', @(src, event) updatePlot()) ...
    uicontrol('Style', 'slider', 'Min', 0.001, 'Max', 0.1, 'Value', dt, 'Position', [120, 400, 300, 20], 'Callback', @(src, event) updatePlot()) ...
    uicontrol('Style', 'slider', 'Min', 100, 'Max', 2000, 'Value', N, 'Position', [120, 350, 300, 20], 'Callback', @(src, event) updatePlot()) ...
    ];

% Create axes for plotting
ax = axes('Parent', fig, 'Position', [0.1, 0.1, 0.8, 0.4]);

% Initial plot
updatePlot();  % Manually call the updatePlot function


% Update plot function
    function updatePlot()
        
        % Get current slider values
        mu = get(h_sliders(1),'Value');
        sigma = get(h_sliders(2),'Value');
        s = get(h_sliders(3),'Value');
        dt = get(h_sliders(4),'Value');
        N = round(get(h_sliders(5),'Value'));
        
        % Run stochastic simulation with updated parameters
        alpha = simulateStochasticProcess(mu, sigma, dt, N);
        
        % Define time vector based on the simulation duration
        T = N * dt;
        t = dt:dt:T;
        
        % Update plot based on simulation results
        plot(ax, t, alpha, 'LineWidth', 1);
        xlabel('Time t');
        ylabel('Stochastic   Order \alpha');
        title(['\mu = ', num2str(mu), ', \sigma = ', num2str(sigma), ', s = ', num2str(s), ', \Delta t = ', num2str(dt), ', N_T = ', num2str(N)]);
        grid on;
        
        % update the labels:
        set(h_labels(1),'String',sprintf('mu = %g',mu));
        set(h_labels(2),'String',sprintf('sigma = %g',sigma));
        set(h_labels(3),'String',sprintf('s = %g',s));
        set(h_labels(4),'String',sprintf('dt = %g',dt));
        set(h_labels(5),'String',sprintf('NT = %g',N));
        
    end


% Function to simulate stochastic process
    function alpha = simulateStochasticProcess(mu, sigma, dt, N)
        sd = sqrt(dt);
        dB = sd * randn(1, N);
        B = cumsum(dB);
        alpha = mu + sigma * B;
    end

end

[Voss]

Here's an untested version of your program that uses uilabels with LaTeX interpreters:

GUI() % run the main function


function GUI() % your script is now a function with the other functions nested in it

% Initialize figure
fig = uifigure('Position', [100, 100, 1000, 600], 'Name', 'Interactive Stochastic Fractional Order Analysis');

% Initial parameters
mu = 0.2;
sigma = 0.2;
s = 100;
dt = 0.01;
N = 1000;
T = N * dt;

% Create sliders and labels for adjusting parameters
h_labels = [ ...
    uilabel(fig, 'Position', [20, 550, 100, 20], 'Interpreter', 'latex') ...
    uilabel(fig, 'Position', [20, 500, 100, 20], 'Interpreter', 'latex') ...
    uilabel(fig, 'Position', [20, 450, 100, 20], 'Interpreter', 'latex') ...
    uilabel(fig, 'Position', [20, 400, 100, 20], 'Interpreter', 'latex') ...
    uilabel(fig, 'Position', [20, 350, 100, 20], 'Interpreter', 'latex') ...
    ];
h_sliders = [ ...
    uislider(fig, 'Limits', [0 1], 'Value', mu, 'Position', [120, 550, 300, 20], 'ValueChangedFcn', @(src, event) updatePlot()) ...
    uislider(fig, 'Limits', [0 1], 'Value', sigma, 'Position', [120, 500, 300, 20], 'ValueChangedFcn', @(src, event) updatePlot()) ...
    uislider(fig, 'Limits', [100 500], 'Value', s, 'Position', [120, 450, 300, 20], 'ValueChangedFcn', @(src, event) updatePlot()) ...
    uislider(fig, 'Limits', [0.001 0.1], 'Value', dt, 'Position', [120, 400, 300, 20], 'ValueChangedFcn', @(src, event) updatePlot()) ...
    uislider(fig, 'Limits', [100 2000], 'Value', N, 'Position', [120, 350, 300, 20], 'ValueChangedFcn', @(src, event) updatePlot()) ...
    ];

% Create axes for plotting
ax = uiaxes(fig, 'Units', 'normalized', 'Position', [0.1, 0.1, 0.8, 0.4]);

% Initial plot
updatePlot();  % Manually call the updatePlot function


% Update plot function
    function updatePlot()
        
        % Get current slider values
        mu = get(h_sliders(1),'Value');
        sigma = get(h_sliders(2),'Value');
        s = get(h_sliders(3),'Value');
        dt = get(h_sliders(4),'Value');
        N = round(get(h_sliders(5),'Value'));
        
        % Run stochastic simulation with updated parameters
        alpha = simulateStochasticProcess(mu, sigma, dt, N);
        
        % Define time vector based on the simulation duration
        T = N * dt;
        t = dt:dt:T;
        
        % Update plot based on simulation results
        plot(ax, t, alpha, 'LineWidth', 1);
        xlabel(ax,'Time t');
        ylabel(ax,'Stochastic   Order \alpha');
        title(ax,['\mu = ', num2str(mu), ', \sigma = ', num2str(sigma), ', s = ', num2str(s), ', \Delta t = ', num2str(dt), ', N_T = ', num2str(N)]);
        grid(ax,'on');
        
        set(h_labels(1),'Text',sprintf('\mu = %g',mu));
        set(h_labels(2),'Text',sprintf('\sigma = %g',sigma));
        set(h_labels(3),'Text',sprintf('s = %g',s));
        set(h_labels(4),'Text',sprintf('\Delta t = %g',dt));
        set(h_labels(5),'Text',sprintf('N_T = %g',N));
        
    end


% Function to simulate stochastic process
    function alpha = simulateStochasticProcess(mu, sigma, dt, N)
        sd = sqrt(dt);
        dB = sd * randn(1, N);
        B = cumsum(dB);
        alpha = mu + sigma * B;
    end

end

[Yamina chbak]

Thanks you @Voss for your help with the code. I really appreciate it!

[Voss]

You're welcome!