Hi,

How can I access the elements of a BandMatrix? The following does not work:

Code: Select all

BandMatrix<double> myMatrix(5,5,1,1);
myMatrix(1,1) = 2.2;

And how can I initialize the banded matrix?

Thanks for your help.

Luis Manuel

When you have a bandMatrix, the only way to address it is by addressing its (sub/super-)diagonals, with the diagonal(index) method, which returns a normal expression that you can initialize in the usual ways.

Code: Select all

myMatrix.diagonal(1).setZero(); // fill first super-diagonal with zeros
myMatrix.diagonal(-1).setConstant(2); // fill first super-diagonal with twos
myMatrix.diagonal(0) = somevector
myMatrix.diagonal(1)(2) = 5; // write 5 as position 2 into the 1st superdiagonal


Ok, not what I was hoping for, but it does provide a way to access the elements.

Thanks for the quick reply,

Saludos,

Luis Manuel