CODEWITHSUNDEEP
c++mpiarmadillo
CKM
CKM

Reputation: 1971

Using Armadillo Sparse Matrices in MPI

I am trying to initialise Armadillo sparse matriix sp_mat within MPI as follows:

if(rank==0)
{  // some code for locations, values
    sp_mat X(locations,values)
}
// this is where I want to use X
if(rank==0)
   some_fun(X)

As you can see, Armadillo constructor is local to the if block and as such can not use it after if block. Putting the same question in another way:

extern sp_mat X
if(rank==0)
{  // some code for locations, values
    sp_mat X(locations,values)
}
// this is where I want to use X
 if(rank==0)
   some_fun(X)

Using extern sp_mat X before if block also does not help (I got undefined reference error).
How can I initialise X and reuse it afterward?

Upvotes: 0

Views: 291

Answers (2)

hbrerkere
hbrerkere

Reputation: 1605

Rather than using pointer tricks, the much cleaner std::move() from C++11 can be used:

sp_mat X;

if(rank==0)
{  // some code for locations, values
    X = std::move( sp_mat(locations,values) );
}

Upvotes: 1

Daniel Langr
Daniel Langr

Reputation: 23497

Use (smart) pointers:

std::unique_ptr<sp_mat> X; // or std::shared_ptr<sp_mat> or sp_mat*
if (rank == 0) {
   // some code for locations and values     
   X = std::unique_ptr<sp_mat>(new sp_mat(locations, values));
}
...
if (rank == 0)
   some_fun(*X);

Upvotes: 1

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