我有几个平面单轴测试的数据，我想绘制应力应变图，并把杨氏模量（定义为应力应变图的斜率）放在一个最终包含所有杨氏模量的列表中。
我写了下面的代码，但是matlab没有生成任何图形，也没有保存到我的计算机上：

% Step 1: Define the directory where your text files are located
directory = 'C:\Users\Biologisch';

% Step 2: Get a list of files in the directory
files = dir(directory);

% Define the column indices you want to extract
columnIndices = [1, 2, 3];  % Modify this as per your requirement

% Define custom names for the result lists
listNames = {'Crosshead', 'Load', 'Time'};  % Modify this with your custom names
all_E = [];

% Step 3: Initialize result lists with custom names to store the results for each column
numColumns = numel(columnIndices);
resultLists = cell(1, numColumns);
for i = 1:numColumns
     resultLists{i} = [];
end

W0 = 45;               %Breedte begin [mm]
D = 4*10^-3;           %Dikte [mm]
W = 40;                %Breedte eind
Area = (D)*(W0)*10^(-6);

% Number of lines to skip (in this case, 8 lines)
linesToSkip = 8;

% Initialize divisionResultsList as an empty cell array
divisionResultsList = cell(1, length(files));

% Step 4: Iterate over the list of files
set(0, 'DefaultFigureVisible', 'on');
for i = 1:length(files)
    filename = files(i).name;
    
    % Step 5: Check if the file is a text file
    if endsWith(filename, '.txt')
        
        % Open the text file
        fileID = fopen(fullfile(directory, filename));
        
        % Skip the first 8 lines
        for j = 1:linesToSkip
            fgetl(fileID);
        end
        
        % Read the remaining lines using textscan
        data = textscan(fileID, '%f');
        
        % Close the file
        fclose(fileID);
        
        % Calculation of stress and strain
        crossheadColumn = data{columnIndices(1)};
        loadColumn = data{columnIndices(2)};
        Stress = loadColumn ./ Area;
        L0 = crossheadColumn(1);
        %calculate strain from crosshead data
        Strain_length = (crossheadColumn-L0)/L0;   
        Strain_width = (W0-W)/W;

        % Store the division results in the divisionResultsList
        divisionResultsList{i} = Stress;
        
        p = polyfit(Strain_length,Stress,1);
        f = polyval(p,Strain_length);     % To fit the polynomial on the preferred x coordinates
        E    = p(1)
        all_E = [all_E;E];
        
        %plot stress-strain curve
        figure(1)
        plot(Strain_length,Stress,'b')
        hold on 
        plot(Strain_length,f,'r')
        xlabel('Strain')
        ylabel('Stress [MPa]')
        title(['File: ', files(i).name])
        legend('Stress-strain curve','Linear fit')
        hold off

        %save plot to folder
        saveas(gcf, fullfile(directory, 'Stress-strain curve', [filename '.png']));
    end
end