Hi lulu,
Based on my comprehension of the question,the initial condition "fr = 0.05 +0.0001*(1+sin(k*x))" is not showing any sinusoidal perturbation,whereas the initial condition "fr = @(x) 0.05 +0.0001*(1+sin(k*x))" works as expected.
The initial condition "fr = 0.05 +0.0001*(1+sin(k*x))" creates a 1x101 double vector.The following errors have been encountered after running "code.m".
Similarly the initial condition for "gr =0.0+0.0001*(1+sin(k*x))" which creates a 1x101 double vector.As seen from the above picture,we can see that error occured at line 115 which traces back to line 88.In line 88, the use of "gr(x)" is causing the issue, inorder to access a value of an array the index must be a positive integer.This condition is failed as the propogated "x" value in line 88 is not an integer.
In contrast, the initial condition "fr = @(x) 0.05 +0.0001*(1+sin(k*x))" creates a function handle. This code performs as anticipated, as the function handle operates effectively with both double and integer parameters in the provided code.
