Implement a matvec method for the COO matrix class

[KyleVaughn]

Description:

Add a matvec function to the SparseMatrix_COO class that conducts matrix-vector multiplication. The function takes the x vector and the A matrix (in COO) from function inputs and then conducts matrix-vector multiplication (Ax=b). The resulting b vector is stored in a newly created vector and returned as function output.

Tasks:

• [x] Add function declaration in parent class
• [x] Add function definition
• [x] Initialize the output vector
• [x] Conduct matrix-vector multiplication in COO format and write result to output vector
• [x] Return the output vector

Definition of done:

The matvec method can conduct COO matrix-vector multiplication and passes the test.

[Lazy-Beee]

Edited the API to avoid memory leak: void matvec(fp_type vecin, fp_type vecout)

[KyleVaughn]

Review by @maxzog

[maxzog]

Review: The description and tasks are pretty clear in what the issue is and how it will be solved. I'm not a C++ programmer by trade so this comment may be moot, but perhaps it'd be helpful to describe where you will be creating the output vector and how it will be returned to the user. Does your function operate on a pointer to an output vector, does it take in the vector data (?), or does it create the vector in the function? For example, in HW2 we had to perform N multiplications - would your function have that capability by modifying an existing output vector or would the result of the output have to be cumulatively summed by the user?