GetSubで行列の一部を抜き出し

{
gROOT->Reset();


TMatrixD m, n;

m.ResizeTo(3,3,-1);
n.ResizeTo(3,3,-1);

m[0][0] = 1.0; m[0][1] = 2.0; m[0][2] = 3.0;
m[1][0] = 4.0; m[1][1] = 8.0; m[1][2] = 6.0;
m[2][0] = 7.0; m[2][1] = 8.0; m[2][2] = 9.0;

n.Print();//3*3のまま

n += m.GetSub(0,1,0,1,"S");//"S"は省略可

n.Print();//2*2に縮小される
m.Print();

}
実行結果

3x3 matrix is as follows

| 0 | 1 | 2 |
------------------------------------------------------------------
0 | 0 0 0
1 | 0 0 0
2 | 0 0 0


2x2 matrix is as follows

| 0 | 1 |
------------------------------------------------------------------
0 | 1 2
1 | 4 8


3x3 matrix is as follows

| 0 | 1 | 2 |
------------------------------------------------------------------
0 | 1 2 3
1 | 4 8 6
2 | 7 8 9