How to plot the function?

Hello. Could you please help me? I am not sure how to plot this function using Matlab. I am new to Matlab, so just trying =(

Answer 1

[Image Analyst]

Can you tell us what the values of a, b, k, t, and epsilon are? Then just take it one term at a time. And there is an ambiguity around x because of missing parentheses. Can you tell us if x is inside the sine argument, or between the sin and cos terms?

a = 2;
b = 1;
c = 1;
k = 1;
t = 1;
epsilon = 1;
x = linspace(0, 5*pi, 1000);
for index = 1 : numel(x)
	thisx = x(index);
	term1 = (2 * epsilon * a^2) / (pi^2 * b * (a - b));
	term2 = sin(pi * k * b / a) / k^2;
	term3 = sin(pi * k * thisx / a); % Does x really go here like this???
	term4 = cos(pi * k * c * t / a);
	f(index) = term1 * sum(term1 .* term2 .* term3);
end
plot(x, f, 'b-', 'LineWidth', 2)
grid on
xlabel('x');
ylabel('f');

[Denis]

Hi! Thanks.

Sorry, now the entry is correct.

I don't know the values for the constant. Below is general task, I've alreade get the f(x) equation from initial data, but still have ploblems with the "generate surface graph"

[Image Analyst]

OK that's the formula I put in. If you don't know the values of the constant parameters, then you cannot plot it.

I have no idea about "generate surface graph". Where did you get that from? Is this a homework? If so, read this link: How do I get help on homework questions on MATLAB Answers? - MATLAB Answers - MATLAB Central

You can't really get a surface unless you have another axis. f(x) is a one dimensional signal. Does any of the other parameters vary? Like k or t maybe? If so you could use surf to plot f(x, k) or f(x, t).

a = 2;
b = 1;
c = 1;
k = 1;
t = 1;
epsilon = 1;
x = linspace(0, 5*pi, 1000);
for index = 1 : numel(x)
    thisx = x(index);
    term1 = (2 * epsilon * a^2) / (pi^2 * b * (a - b));
    % Sum over k
    for k = 1 : 1000
        term2 = sin(pi * k * b / a) / k^2;
        term3 = sin(pi * k * thisx / a); % Does x really go here like this???
        term4 = cos(pi * k * c * t / a);
        f(index, k) = term1 * sum(term1 .* term2 .* term3);
    end
end
k = 1 : 1000;
surf(x, k, f, 'EdgeColor','none')
grid on
xlabel('x');
ylabel('f');

[Torsten]

Here is the code for one value of t.

Add a second loop over t-values to produce a surface plot.

a = 2;
b = 1;
c = 10;
k = 1;
t = 1;
epsilon = 1;
term1 = (2 * epsilon * a^2) / (pi^2 * b * (a - b));
x = linspace(0, a, 1000);
f = zeros(size(x));
for index = 1 : numel(x)
    thisx = x(index);
    % Sum over k
    for k = 1 : 1000
        term2 = sin(pi * k * b / a) / k^2;
        term3 = sin(pi * k * thisx / a); % Does x really go here like this???
        term4 = cos(pi * k * c * t / a);
        f(index) = f(index) + term2 * term3 * term4;
    end
end
f = f * term1;
plot(x, f)
grid on
xlabel('x');
ylabel('f');