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c++cmatlabsparse-matrixequivalent

Any C++/C equivalent function with sparse in MATLAB

I tried to port m code to c or cpp.

In my code there is a line

A = sparse(I,J,IA,nR,nC);

which converts row index I, col index J, and data IA to sparse matrix A with size nR x nC.

Is there any equivalent code with C++ or C?

An naïve algorithm to duplicate result in full matrix is

double *A;
A = malloc(sizeof(double)*nR*nC);
memset(A, 0, sizeof(double));

for(k=0; k<size_of_IA; k++)
    A[I[k]*nC + J[k]] += IA[k];

Note that if there is common indices, the value is not over overwritten, but accumulated.

Solution

  • Eigen is an example of a C++ math matrix library that cobtains sparse matrices. It overloads operators to make it feel like a built in feature.

    There are many C and C++ matrix libraries. None ship as part of std, nor is there anything built in.

    Writing a good sparse matrix library would be quite hard; your best bet is finding a pre-written one. Recommendation questions are off topic