SparseArray

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SparseArray[rules]

Builds a sparse array according to the list of rules.

SparseArray[rules, dims]

Builds a sparse array of dimensions dims according to the rules.

SparseArray[list]

Builds a sparse representation of list.

• • SparseArray[{{1, 2} -> 1, {2, 1} -> 1}]

• • SparseArray[{{1, 2} -> 1, {2, 1} -> 1}, {3, 3}]

• • M=SparseArray[{{0, a}, {b, 0}}]

• • M //Normal