| Matrix2d m; m << 1,2,3,4; | |
| cout << (m*m).lazy().row(0) << endl; | |
| // this computes only one row of the product. By contrast, | |
| // if we did "(m*m).row(0);" then m*m would first be evaluated into | |
| // a temporary, because the Product expression has the EvalBeforeNestingBit. |