Arrays have incompatible sizes for this operation , ERROR help me fix the code

% Define the variables

clc

w = 2*pi; % angular frequency

L = 1; % length of domain

f = @(x) x.^2; % function to be expanded

g = @(x) x; % another function to be expanded

% Define the function y(x,t)

% Calculate the A_n coefficients

n = 20; % number of terms in the expansion

A = zeros(1, n);

for i = 1:n

A(i) = 2/L*integral(@(x) f(x).*sin(i*pi*x/L), 0, L);

end

% Calculate the B_n coefficients

B = zeros(1, n);

for i = 1:n

B(i) = 2/(w*L)*integral(@(x) g(x).*sin(i*pi*x/L), 0, L);

end

% Define the function y(x,t)

y = @(x,t)sum(((A.*cos(w*t.*(1:n)) + B.*sin(w*t.*(1:n))).*sin(((1:n).*pi.*x/L))));

% Plot the function over a range of x and t values

x = linspace(0, L, 100);

t = linspace(0, 10, 100);

[X,T] = meshgrid(x,t);

Y = y(X,T);

surf(X,T,Y);

xlabel('x'); ylabel('t'); zlabel('y(x,t)');

Answer 1

[Abhinav]

The line

y = @(x,t)sum(((A.*cos(w*t.*(1:n)) + B.*sin(w*t.*(1:n))).*sin(((1:n).*pi.*x/L))))

is cause of the error, t is a 1x100 array you multiplying it with (1:n) (which is 1x20 array) that is why you are getting the matrix dimension mismatch error. Changing n to 100 resolves the error.

Refer to the following documentation link to learn more about compatible array sizes for basic operation

https://www.mathworks.com/help/matlab/matlab_prog/compatible-array-sizes-for-basic-operations.html

[Reham]

can you help me with this error

Error using surf (line 71)

Z must be a matrix, not a scalar or vector.

Error in Untitled (line 29)

surf(X,T,Y);

it appears when i run the code