prod_var -- Randy Judd's matrix-matrix product variations
   -1 -- direct matrix product using VSIPL function
   -2 -- prod_2:    Alg 1.1.8 Outer Product from G&VL
   -3 -- prod_3:    Alg 1.1.7 Saxpy Version G&VL
   -4 -- prod_3c:
   -5 -- prod_3sv:  Alg 1.1.7 Saxpy Version G&VL using subview
   -6 -- prod_4:    Alg 1.1.5 ijk variant G&VL
   -7 -- prod_4t:   Alg 1.1.5 ijk variant G&VL with tmp storage
   -8 -- prod_4trc:
   -9 -- prod_4tsv:
  -10 -- prod_4dot:
  Options  -1 through -10 use float matrices.
  Options -11 through -20 are the same as the above, but
                          use complex<float> matrices.