CODEWITHSUNDEEP
c++matlabarmadillo
Garima Singh
Garima Singh

Reputation: 1490

Armadillo sparse allocation of a matrix

In Matlab, I allocate space for sparse matrix like this:

%Notice "Const_Block_Upper" is a dense matrix
%Number of nonzero element
nz = size(Const_Block_Upper,1)*size(Const_Block_Upper,2)*No_of_Voxels;
SizeR = No_of_Voxels*size(Const_Block_Upper,1)
SizeC = No_of_Voxels*size(Const_Block_Upper,2);

%Allocates space for sparse matrix of size (SizeR, SizeC) with atmost nz non-zeros
A = spalloc(SizeR, SizeC, nz);

I am wondering if I can do something similar in C++ lib Armadillo. I looked at documentation of Armadillo; however, could not find something similar.

Some help would be appreciated.

Upvotes: 1

Views: 638

Answers (1)

Marcus Müller
Marcus Müller

Reputation: 36433

I wonder at which part of the documentation you looked, because the official documentation contains a lot about the sparse matrix types. For example about batch insertion:

Batch insertion constructors:

form 1: sp_mat(locations, values, sort_locations = true)
form 2: sp_mat(locations, values, n_rows, n_cols, sort_locations = true, check_for_zeros = true)
form 3: sp_mat(add_values, locations, values, n_rows, n_cols, sort_locations = true, check_for_zeros = true)
form 4: sp_mat(rowind, colptr, values, n_rows, n_cols)

EDIT: Ah, I understand your question now; you want to preallocate the space necessary for element storage; I'm afraid there's no possibility to do so with the underlying sparse matrix storage format...

Upvotes: 2

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