Hi,

Apologies for my previous post I still have pending to send an example code but I've had to leave that task aside for the moment, hopefully I'll go back to that soon.

So now I have another question.
I have a templated function that receives a MatrixBase<Derived1>& as template argument. If this argument is a Map how can I declare inside this function I variable of the same type as the type argument of that Map.
example:

template<class Derived1, class Derived2>
Derived1 filterRows(Eigen::MatrixBase<Derived1> &data, Eigen::ArrayBase<Derived2> &boolMap)
{
Derived1 result(data.rows(), data.cols());
int count = 0;
for(int i = 0; i < data.rows(); i++)
if(boolMap(i))
{
result.row(count) = data.row(i);
count++;
}
result.conservativeResize(count, NoChange);
return result;
}

void main()
{
MatrixXd m1 = MatrixXd::Random(50, 20);
Map<MatrixXd> mapm1(m1.data(), 50, 20);
Array<bool, Dynamic, 1> boolMap = Array<bool, Dynamic, 1>::Random(50);
MatrixXd filteredM1;

filteredM1 = filterRows(m1, boolMap);
//filteredM1 = filterRows(mapm1, boolMap);
}

This code as it is works well, but when I uncomment the last line in main and recompile I get an error in the line
Derived1 result(data.rows(), data.cols());

I assume that what I need is to declare result as being the same type as the mapped type. I have tried to declare result as being a MatrixBase<Derived1>::PlainMatrixType or Derived1::PlainObjectType but does compile.

How can I declare result to be of the type mapped by the map?

Thanks,
Martin

typename Derived1::PlainObject

the "typename" keyword is important here!

It works!! it was the missing typename keyword.
Thanks!
Martin