Hi folks,

I am using Eigen for a numerical solver and I have a peculiar problem: I want to create a matrix, which does not actually store the elements but computes them when accessed (I do not want to store it, because it should actually represent a slice of a 3d matrix and that's too large to fit into memory; it is also unfortunately not sparse). Basically I want to create something with a simple getter:

Code: Select all

double element(i, j) {
return /* simple calculation here */;
}

Is there an easy way how to achieve that in Eigen?


Thanks in advance for any suggestions

yes, you can use MatrixXd::NullaryExpr(my_functor), there is an example there: http://eigen.tuxfamily.org/dox-devel/cl ... f78b068a9b