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Given a sparse matrix A with 1 million rows and 10 million nonzero entries, which method is most efficient to solve Ax = b in SciPy?

hard📝 Application Q8 of 15
SciPy - Sparse Matrices (scipy.sparse)
Given a sparse matrix A with 1 million rows and 10 million nonzero entries, which method is most efficient to solve Ax = b in SciPy?
AUse iterative solvers like <code>cg</code> or <code>gmres</code> from <code>scipy.sparse.linalg</code>
BConvert <code>A</code> to dense and use <code>numpy.linalg.solve</code>
CUse <code>spsolve</code> directly on the dense matrix
DManually implement Gaussian elimination
Step-by-Step Solution
Solution:
  1. Step 1: Consider matrix size

    A is very large and sparse, so dense methods are infeasible due to memory.
  2. Step 2: Choose solver type

    Iterative solvers like cg (Conjugate Gradient) or gmres are designed for large sparse systems and scale better.
  3. Final Answer:

    Use iterative solvers like cg or gmres from scipy.sparse.linalg -> Option A
  4. Quick Check:

    Is dense conversion feasible? No. Use iterative methods. [OK]
Quick Trick: Use iterative solvers for very large sparse systems [OK]
Common Mistakes:
MISTAKES
  • Trying to convert large sparse matrix to dense
  • Using direct solvers on huge matrices
  • Ignoring memory constraints

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