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Matrix conversion — Lodestar.Extensions.MathNet

One type, MathNetInterop: it converts a CsrMatrix to and from Math.NET Numerics' sparse matrix, so a caller who already holds Math.NET types can reach Lodestar.Decomposition and the sparse vectorizers without rebuilding a matrix cell by cell.

Both sides store a matrix in compressed sparse row form and both expose those arrays, so each direction is one pass over the stored values rather than a walk over every cell. That is the whole reason this package is worth installing: the conversion anyone can write by hand is the slow one.

Why this package exists at all

Lodestar.Decomposition refused Math.NET for its own kernels — 5.0.0 dates from 2022-04-03 and nothing stable has followed — and writes its own QR, LU and Jacobi SVD instead. Referencing the same library here is not a reversal: decisions/0089 separates the two. Computing with a stale dependency hands its problems to a caller who never asked; converting to a caller's own types hands them nothing they were not already carrying, and a caller who holds no Math.NET types installs nothing.

What is not offered

The dense pair. CsrMatrix.ToDense() already returns a double[,], and Math.NET builds a DenseMatrix from one unaided, so a wrapper would add a member that saves nobody a line. The sparse pair is the one conversion neither side can do for itself.

Types

Type	What it is
MathNetInterop	Converts between CsrMatrix and Math.NET's sparse matrix.

See also

• Sparse matrices — where CsrMatrix is documented.
• Matrix factorization — what a converted matrix is usually for.
• Python → C# equivalence.