Hi,

I'm trying to write a new constructor for my application. I need that the users can write a code like :

Code: Select all

MatrixXd A(n)

and A will be a matrix Nx1, but the constructor doesn't like this expression and returns me a YOU_TRIED_CALLING_A_VECTOR_METHOD_ON_A_MATRIX error.

So I decided to add a new constructor in EIGEN_MATRIX_PLUGIN or EIGEN_MATRIXBASE_PLUGIN with no result. So I try to modify Matrix.h : I remove the constructor EIGEN_STRONG_INLINE explicit Matrix(int dim) and modify the other EIGEN_STRONG_INLINE Matrix(int x, int y) by adding and default value for y:
EIGEN_STRONG_INLINE Matrix(int x, int y = 1), but it still doesn't work. I think it comes from ColsAtCompileTime but I don't know where that variable is updated.

If you have any response or a better idea, I'm open

Thanks

If you want your own matrix class with custom constructors, the easiest way would be to define a new class inheriting Matrix. Since constructors aren't inherited, you could do whatever you want to.

http://eigen.tuxfamily.org/dox-devel/To ... FromMatrix

I'm puzzled, if you write:

MatrixXd A(n)

then you know that A is a vector, so why not using a vector which will bring higher performance as a bonus ?

Thank you, It can be a solution, but I think that will first add new problems ^^

But I've some questions : if I use a class, are the template preserve ? I mean if my new class is "matrix", and if i write matrix u = v + w; the asm code will be u[i] = v[i] + w[i] ?
What are the functions i need to add ? (in the doc you said "a few members") for instance to avoid "impossible to convert 'const Eigen::CwiseNullaryOp<NullaryOp,MatrixType>' in 'matrix'"

@ggael : I know that it's strange, but it's because i'm updating a previous library and thousands of lines of code already exist, and i can't rewrite all. For the future code, it will be naturally better to use Eigen syntax or at least vector instead of always matrix.

EDIT : The error is corrected, I forget some constructors and operators = (for Scalar), (it's quit easy in fact !), but i've still my question about the template

Yes, expression templates are still working. Just check it for yourself (look at the generated assembly!)

OK, I understand, inheriting Matrix is also what I did when starting to use Eigen and keep some minimal level of compatibility

@bjacob & ggael : Thank you for your answers I will check the assembly code but only when i'll go back on linux ^^ (i'm on windows for this project and it seems to be complicated to produce an asm file... (where is gcc -S ? ^^))