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

Question

AVINASH SAHU 2022-7-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1759630-getting-error-while-trying-to-access-the-data-of-the-following-plot

评论： AVINASH SAHU 2022-7-14

采纳的回答： KSSV

在 MATLAB Online 中打开

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') ;

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Answer 1

KSSV 2022-7-14

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1759630-getting-error-while-trying-to-access-the-data-of-the-following-plot#answer_1007010

在 MATLAB Online 中打开

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)')