1%% MatrixMarket matrix coordinate double general
2% This example is 1-based with (optional) nnz
3%
4% This is a 1D mass matrix
5%
6%              1
7%              .
8%             / \
9%            /   \ 0
10%  phi_i  --o  o  o--o--
11%              i  j
12%
13%                 1
14%                 .
15%                / \
16%               /   \ 0
17%  phi_j  --o--o  o  o--
18%              i  j
19%
20%                i     j
21%            | i_ii  i_ij | i
22%  inertia = |            |
23%            | i_ji  i_jj | j
24%
25%  distance(i, j) = d = 1.
26%
27%  i_ii = int_[i,j](phi_i.phi_i) = int_[i,j]((1-x)(1-x)) = i_jj (area under the curve)
28%  i_ij = int_[i,j](phi_i.phi_j) = int_[i,j]((1-x)   x ) = i_ji
29%  i_ji = int_[i,j](phi_j.phi_i) = int_[i,j](   x (1-x)) = d*1./6.
30%  i_jj = int_[i,j](phi_j.phi_j) = int_[i,j](   x    x ) = d*1./3.
31%
32% B <=> mass assembly
33%
34% n m [nnz]
35% i j Bij
36
378 8 22
38
391  1  0.333
402  2  0.333
413  3  0.333
424  4  0.333
435  5  0.333
446  6  0.333
457  7  0.333
468  8  0.333
47
482  1  0.166
493  2  0.166
504  3  0.166
515  4  0.166
526  5  0.166
537  6  0.166
548  7  0.166
55
561  2  0.166
572  3  0.166
583  4  0.166
594  5  0.166
605  6  0.166
616  7  0.166
627  8  0.166
63