[eigen] Optimization for special complex operations

[Carlos Becker <carlosbecker@xxxxxxxxx>]

Hi everyone again. Lately I've been using Eigen with complex numbers to calculate things such as calculating the maximum of the real part or imaginary part of a certain vector. I suppose that trying to take the real part and then use maxCoeff() or minCoeff() would create a possible unnecessary temporary.

Another thing is to be able to do something like:

MatrixXf nn,xx;
xx = nn.colwise().normalized();

Here there are two very different concepts:

• I guess there could be some special functions, in this case only for complex numbers, to be able to perform some special optimizations. I remember we were talking a bit about a special case with Gael on the chat channel.
• Regarding the .normalized() snippet above, I know I am breaking reduction rules, since I am expecting xx and nn to be of the same size in the end. However, I don't know how much is lost if this normalization is done manually with, for instance, a for loop.

Does this make sense? I would like to work on these but I don't want to introduce code that would not make sense or break rules. I only have a small insight of what eigen looks like inside.

Carlos