Implement a matvec method for the ELL matrix class

[KyleVaughn]

Description:

The SpMV program performs sparse matrix multiplication for various formats, one of these formats is the ELL storage type, this method perform matrix-vector multiplication (Ax=B) when the sparse matrix storage format is ELL. This method will require the input matrix A, the input matrix will need to be stored in a ELL matrix type and will need ELL_row_ptrs and ELL_col_ptrsto accurately assign the matrix, it will also need a vecin and vecout to write the x and B vectors. The multiplication step would require x vector to be informed by the ELL_row_ptrs and ELL_col_ptrs to ensure elements are multiplied correctly.

Tasks:

• [ ] Add a function declaration in the parent class
• [ ] Define the function definition in the SpMV_ELL.
• [ ] ensure ELL tests assembleStorage and disassembleStorage tests pass
• [ ] Ensure the vectorin x and matrix A exist in memory
• [ ] Convert the matrix A to an ELL sparse storage format
• [ ] Perform the matrix multiplication
• [ ] Ensure that vectorout B exists in memory
• [ ] Write to B
• [ ] Return B

Definition of done:

The vectorout should be outputted to the right location and the matrix vector multiplication should happen without errors. It should also pass the tests.

[KyleVaughn]

Review by @AnvayPradhan

[Lazy-Beee]

I would suggest using the function interface virtual fp_type* matvec(fp_type* vecin) and I'll add this to the SparseMatrix class.

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Edit: change the api to avoid memory leak void matvec(fp_type* vecin, fp_type* vecout)

[AnvayPradhan]

Recommend ensuring ELL tests assembleStorage and disassembleStorage tests pass before testing this matvec method

[prathameshnakhate]

@AshrayMohit I have made ELL matrix class in the ell branch. I have implemented setCoefficient() method such that -1 entries in ColIdx and Val correspond to the zero entries in the matrix(represented by * in HW2 pdf).

I understand that this implementation will fail if the matrix has negative entries. In that case, we can decide on a different placeholder for the zero entry.

Just wanted to let you know since you will require this information while implementing the matvec method