Test problems

The test matrices are download from the MatrixMarket (http://math.nist.gov/MatrixMarket). These are square matrices of size ranging from 2534 to 94069. These matrices are in the MatrixMarket coordinate format. For example, for the following $5\times 5$ sparse matrix with 8 nonzero entries,

$$\left( \begin{array}{ccccc} 1 & 0 & 0 & 6 & 0 \\ 0 &... ...0 & 33.32 \\ 0 & 0 & 0 & 0 & 12 \\ \end{array} \right)$$ (2)

is stored in the MatrixMarket coordinate as

%%MatrixMarket matrix coordinate real general
 5  5  8
    1     1   1.000e+00
    2     2   1.050e+01
    3     3   1.500e-02
    1     4   6.000e+00
    4     2   2.505e+02
    4     4  -2.800e+02
    4     5   3.332e+01
    5     5   1.200e+01

Because matrices from MatrixMarket may contain sparse patterns without any entry values, for simplicity all matrix files have been converted to a form with only the sparse pattern. Thus for example the above matrix will be in the form

 5  5  8
    1     1  
    2     2  
    3     3  
    1     4  
    4     2  
    4     4  
    4     5  
    5     5

All the matrix entries are set to one after reading in the sparse pattern.