MATLAB: How to use callbacks to plot data from an existing matlab data file

callbackcallbacksguiguideMATLABmatlab guiplot with slidersliderslider plot

Hello. I am having trouble grasping the way callbacks work to get my user interface code working properly. What I'm trying to do is this:
I have 4 sliders that select the indexes for picking up data from an already existing .m file (a 5D array), after which a for loop runs through the last dimension to get the y values for my x-y plot.
Right now the code does not work because the way my S.y function is defined isn't allowed – it should be a cell array, but I don't really think I need that.
All of what I need is pretty much coded, but the way my lines for S.y and y are coded won't allow the update functions to work properly.
function [] = slider_plot()
load wavelength.mat;
load grating_spacing.mat;
load diffraction_order.mat;
load angle_falling.mat;
load angle_dispersion_1_dgrating.mat;
% Plot different plots according to slider location.
% Define figure, normalized position can be adjusted to fit individual
% monitors.
S.fh = figure('units','normalized',...
    'Position', [0.515 0.025 0.415 0.87]);
% Define axes so that room is available in figure window for sliders
S.ax = axes('unit','normalized',...
          'position',[0.03 0.1 0.5 0.85]);
% General function
for l = 1:length(wavelength)
S.y(l) = @(par) angle_dispersion_1_dgrating(l, par(1), par(2), par(3), par(4));
end
% Define inital parameter values
S.a = 1; %angle falling
S.b = 1; %diffraction order
S.c = 1; %grating spacing
S.d = 1; %transmission or reflection, 1 - transmission
% x axes
S.x = wavelength;
hold on;
% Plot curve
S.p2 = plot(S.x,S.y);
hold off;
update(S);
% Slider for angle falling parameter:
S.aSlider = uicontrol('style','slider',...
               'unit','normalized',...
               'min',1,'max',length(angle_falling),'value', S.a,...
               'position',[0.53 0.9 0.2 0.05],...
               'sliderstep',[1 1],...
               'callback', {@SliderCB, 'a'}); 
% Add a text uicontrol to label the slider.



txta = uicontrol('Style','text',...
     'unit','normalized',...
               'position',[0.2 0.11 0.7 0.02],...
     'String','Angle of incidence, deg.');
% diffraction order Slider:
S.bSlider = uicontrol('style','slide',...
               'unit','normalized',...
               'min',1,'max',length(diffraction_order),'value', S.b,...
               'sliderstep',[1 1],...
               'callback', {@SliderCB, 'b'});
% Add a text uicontrol to label the slider.
txtb = uicontrol('Style','text',...
     'unit','normalized',...
     'String','Diffraction order');       
% grating spacing Slider:
S.cSlider = uicontrol('style','slide',...
               'unit','normalized',...
               'min',1,'max',length(grating_spacing),'value', S.c,...
               'sliderstep',[1 1],...
               'callback', {@SliderCB, 'c'});
% Add a text uicontrol to label the slider.
txtc = uicontrol('Style','text',...
     'unit','normalized',...
     'String','Grating spacing, m');
% transmission or reflection, 1 - transmission Slider:
S.dSlider = uicontrol('style','slide',...
               'unit','normalized',...
               'min',1,'max',2,'value', S.d,...
               'sliderstep',[1 1],...
               'callback', {@SliderCB, 'd'});
% Add a text uicontrol to label the slider.
txtd = uicontrol('Style','text',...
     'unit','normalized',...
     'String','Transmission-reflection select');       
guidata(S.fh, S);  % Store S structure in the figure
end
% Callback for all sliders defined above
function SliderCB(aSlider, EventData, Param)
S = guidata(aSlider);  % Get S structure from the figure
S.(Param) = get(aSlider, 'Value');  % Any of the 'a', 'b', etc. defined
update(S);  % Update the plot values
guidata(aSlider, S);  % Store modified S in figure
end
% Plot update function, creates new y-vector for plot and replaces the plot
% S.p2 with new y-vector
function update(S)
load wavelength.mat;
for l = 1:length(wavelength)
y(l) = S.y([S.a, S.b, S.c, S.d]);
end
set(S.p2, 'YData', y);  % Replace old plot with new plotting values
end

Best Answer

Function handles are scalar by definition: they cannot be formed into an array of function handles, as you are trying to do. To store multiple function handles you will need to put them into a cell array:
for kk = 1:numel(...)
    S.y{kk}) = @(par) ...
end
and then when calling those functions:
for kk = 1:numel(S.y)
    S.y{kk}(...)
end
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