"For any case when should we use element wise and not element wise operation. I know how it works, but not exactly where to use element wise operation"
Matrix operations are for linear algebra, so if you are not doing linear algebra, then use element-wise operations. In almost all cases when beginners don't know what linear algebra is, or what matrix multiplication is, or why matrices have such strange ways of behaving, they should be using element-wise operations.
"When should we use or why should we use CBF(1,q) with indexing and simply 'CBF' without any indexing."
These are two completely different operations:
- Use indexing when you want to redefine some/all elements of an array.
- Allocate an array to a variable (what you called "without any indexing") when you want to allocate the RHS to a variable.
