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Vector Space Span


The vector space span of a subset S of a vector space V over a field F is the set of all finite linear combinations of vectors in S. It is the smallest subspace of V containing S. For S={v_1,...,v_k},

 Span(S)={sum_(i=1)^ka_iv_i:a_1,...,a_k in F}.

For an infinite set S, each individual linear combination still uses only finitely many vectors. The span of the empty set is {0} (Axler 2024, pp. 28-29).

For example, the span of two vectors v_1 and v_2 in a real vector space V is the subspace

 Span(v_1,v_2)={rv_1+sv_2:r,s in R}.

A set of vectors m={v_1,...,v_n} can be tested to see if they form a spanning set of n-dimensional space using the following Wolfram Language function:

  SpanningVectorsQ[m_List?MatrixQ] :=
    (NullSpace[m] == {})

See also

Linear Combination, Null Space, Span, Spanning Set, Vector Basis, Vector Space

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References

Axler, S. Linear Algebra Done Right, 4th ed. Cham, Switzerland: Springer, 2024. https://doi.org/10.1007/978-3-031-41026-0.

Referenced on Wolfram|Alpha

Vector Space Span

Cite this as:

Weisstein, Eric W. "Vector Space Span." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/VectorSpaceSpan.html

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