HSL_MC65: Construct and manipulate matrices in compressed sparse row format

A suite of Fortran 95 procedures for constructing and manipulating sparse matrix objects in compressed sparse row format.

For a general sparse matrix, the compressed sparse row format consists of three arrays, PTR, COL and VAL. PTR holds the starting positions of the rows in the COL and VAL arrays. The indices of the entries of row I are held in COL(PTR(I):PTR(I+1)-1) and the corresponding values are held in VAL(PTR(I):PTR(I+1)-1). However, the user should not need to deal with these arrays individually; HSL_MC65 encapsulates them in a sparse matrix object of the derived type HSL_ZD01_TYPE. HSL_MC65 provides procedures that perform basic operations, such as sparse matrix summation and multiplication, on these sparse matrix objects. There is an option for omitting VAL, that is, for a pattern-only matrix.