Error message: Matrix Dimensions must agree

Not sure what I am doing wrong:

syms x
n = 0:1:100;
t = 0:0.1:50;
lamda = (n .* pi);
u = (100 .* cosd(lamda .* x) + (sind(lamda .* x)) .* (exp((-lamda .^ 2) .* t) ;

fplot(t,u)
grid on

Thank you

Answer 1

[Vinay]

Hi @Ian Strahley,

The issue arises due to mismatch in matrix dimensions between "exp((-lambda .^ 2))" and "t", which are of sizes "1x101" and "1x501", respectively.

To resolve this issue, adjust the dimensions of the vector "t" to 1x101. This can be achieved by modifying the definition of t as follows:

t = 0:0.5:50;

I hope this resolves the query!

Answer 2

[VBBV]

Hi @Ian Strahley,

• Use linspace to divide the data points uniformly for variables in the equation.
• use a function handle, when plotting function fplot
• Ensure the parenthesis are closed correctly

n = linspace(0,100,10);
t = linspace(0,50,10);
lamda = (n .* pi);
u = @(x) 100 .* cosd(lamda .* x) + (sind(lamda .* x) .* exp((-lamda .^ 2) .* t)) ;
fplot(u,[0 1])
grid on

●

[Walter Roberson]

use a function handle, when plotting function fplot

There are two different fplot() functions, one of which is defined for function handles, and the other (closely related) one is defined for symbolic expressions and symbolic functions. In theory, using fplot() with symbolic expressions should be fine, if a bit slower than the function handle case.