Getting error while trying to access the data of the following plot.

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);
    
    fplot(P, [0 1])
    
    
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 have tried to access its data but getting error as .....

 Index exceeds the number of array elements. Index must not exceed 0.

using the code

 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

[KSSV]

You are plotting the data using fplot. This will give you the function, which you have used to plot when you try to extract the data from figure. If you insist to extract the data from figure (which is not necessary) you may consider using plot.

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)')

[AVINASH SAHU]

Thank you so much! you really saved my day

[AVINASH SAHU]

We are getting Data values as 1 x 100. How to reduce it to 1 x 6 i.e. getting values of y w.r.t x at 0, 0.2, 0.4, 0.6, 0.8, 1. Thanks in advance!

[KSSV]

Thats a simple problem...you do it.

[AVINASH SAHU]

Okay thanks for help.

[AVINASH SAHU]

not able to find out the solution.