how can I plot

sigma_0 = 2;

r = 1:0.1:2;

ksi = 1./r;

theta = 0;

sigma_r = (1/2.*sigma_0.*(1-(ksi.^2)))-(1/2.*sigma_0.*(1+(3.*(ksi.^4))-(4.*(ksi.^2))).*cos(2.*theta))

How can I show this as theta 0, 90, 180 and 270, all in one chart, depending on sigma r?

[Manikanta Aditya]

Hey,

Check this:

% Constants
sigma_0 = 2;
theta_deg = [0, 90, 180, 270]; % Degrees
theta_rad = deg2rad(theta_deg); % Convert degrees to radians

% Variable
r = 1:0.1:2;

% Pre-allocate sigma_r for efficiency
sigma_r = zeros(length(r), length(theta_rad));

% Calculate sigma_r for each theta
for i = 1:length(theta_rad)
    theta = theta_rad(i);
    ksi = 1./r;
    sigma_r(:, i) = (1/2.*sigma_0.*(1-(ksi.^2))) - (1/2.*sigma_0.*(1+(3.*(ksi.^4))-(4.*(ksi.^2))).*cos(2.*theta));
end

% Plotting
figure; % Create a new figure
hold on; % Hold on to plot multiple lines
colors = ['r', 'g', 'b', 'k']; % Colors for each theta
for i = 1:length(theta_rad)
    plot(r, sigma_r(:, i), 'Color', colors(i), 'DisplayName', sprintf('\\theta = %d°', theta_deg(i)));
end
hold off;

xlabel('r');
ylabel('\sigma_r');
title('\sigma_r vs. r for \theta = 0, 90, 180, and 270 degrees');
legend('show');
grid on;

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Hassaan]

sigma_0 = 2;
r = 1:0.1:2; % Range of r
theta_deg = [0, 90, 180, 270]; % Angles in degrees
theta_rad = deg2rad(theta_deg); % Convert angles to radians

% Preallocate matrix for sigma_r values
sigma_r = zeros(length(r), length(theta_rad));

% Calculate sigma_r for each theta
for i = 1:length(theta_rad)
    ksi = 1./r;
    theta = theta_rad(i);
    sigma_r(:, i) = (1/2.*sigma_0.*(1-(ksi.^2))) - (1/2.*sigma_0.*(1+(3.*(ksi.^4))-(4.*(ksi.^2))).*cos(2.*theta));
end

% Plot sigma_r vs r for each theta
figure;
plot(r, sigma_r, 'LineWidth', 2);
xlabel('r');
ylabel('\sigma_r');
title('\sigma_r vs r for Different \theta Values');
legend('0°', '90°', '180°', '270°');
grid on;

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