title: Increment sparse matrix
body: <p>I am currently manipulating a very huge matrix so I had to use CSR format like this : <a href="https://en.m.wikipedia.org/wiki/Sparse_matrix" rel="nofollow noreferrer">https://en.m.wikipedia.org/wiki/Sparse_matrix</a></p>
  
  <p>I managed to convert a normal matrix to a CSR matrix with the 3 arrays IA, JA and A like in the Wikipedia page.
  However, I am still confused about this format. How can I do if for example I want to increment the element of line n and column m of the CSR matrix? If for example I want to increment the element at the line n and column m by 1, how will the 3 arrays change?
  Thank you very much for your help. </p>