I am getting data values as 1 x 100. How to reduce it to 1x6 i.e, require values of y w.r.t x at 0.2 0.4, 0.6, 0.8

syms x
warning off
alpha = -0.1;
sigma = 0.1;
eps = -0.1;
e = 0.2;
a = 2;
lambda = 2;
M = 4;

psi_list = [10, 30, 40, 50, 5, 15, 20, 25];
figure
hold on
for i = 1:numel(psi_list)
    psi = psi_list(i);
    hbar = @(x) a - a.*x  + x;
    A1 = eps + alpha^3 + (3 * sigma^2 * alpha);
    B1 = @(x) (-3 * lambda * M) * ((hbar(x).^2) + (2 .* hbar(x) .* alpha) + (sigma^2) + (alpha^2));
    
    a1 = @(x) tanh(M .* hbar(x));
    b1 = @(x) 1 - ((tanh(M .* hbar(x))).^2);
    c1 = (M * alpha) - ((M^3 * A1)/3);
    d1 = 2 * (M^2) * (1 + lambda);
    
    C1 = @(x) a1(x) + (b1(x) .* c1);
    D1 = @(x) d1 .* ((hbar(x).^3) + (3 .* (hbar(x).^2) .* alpha) + (3 .* hbar(x) .* (alpha)^2) + (3 .* hbar(x) .* (sigma)^2) + eps + (3 * alpha * (sigma^2)) + (alpha^3));
    
    f1 = @(x) B1(x) + (3 * lambda .* C1(x) .* hbar(x)) + (3 * lambda .* C1(x) .* alpha) + (D1(x) .* C1(x));
    f2 = @(x) 12 * (M^2) * (1 + lambda) .* C1(x);
    f3 = psi * (e^3);
    f4 = (1 + lambda) *180 * ((1 - e)^2);  % 180 is not given in paper
    f5 = 1/(2 + lambda);
    
    F = @(x) ((f5 .* f1(x))./f2(x)) + (f3/f4);
    
    q1 = @(x) hbar(x) ./ (2 .* F(x));
    Q1 = integral(q1,0,1);
    
    q2 = @(x) 1./(F(x));
    Q2 = integral(q2,0,1);
    
    Q = Q1/Q2;
    
    p1 = @(x) (1./F(x)) .* ((0.5 .* hbar(x)) - Q);
    P = @(x) integral(p1,0,x);
    
    
    xi = linspace(0,1) ; 
    PP = zeros(size(xi)) ; 
    for j = 1:length(xi)
        PP(j) = P(xi(j)) ;
    end
    plot(xi,PP)
    
    
end
legend(num2str(psi_list'))
ylim([0 1])
set(gca, 'ytick', 0:0.1:1);
set(gca, 'xtick', 0:0.2:1);
xlabel('x')
ylabel('P(x)')

I am extracting data using the following

 open('example.fig');
h = findobj(gca,'Type','line')

x1=get(h(1),'Xdata') ;
y1=get(h(1),'Ydata') ;

x2=get(h(2),'Xdata') ;
y2=get(h(2),'Ydata') ;

x3=get(h(3),'Xdata') ;
y3=get(h(3),'Ydata') ;

x4=get(h(4),'Xdata') ;
y4=get(h(4),'Ydata') ;

x5=get(h(5),'Xdata') ;
y5=get(h(5),'Ydata') ;

x6=get(h(6),'Xdata') ;
y6=get(h(6),'Ydata') ;

x7=get(h(7),'Xdata') ;
y7=get(h(7),'Ydata') ;

x8=get(h(8),'Xdata') ;
y8=get(h(8),'Ydata') ;

Answer 1

[Jon]

I don't have the symbolic toolbox, but in ordinary MATLAB you would use interp1 for this