A basis of a vector space VV is a set of vectors BB such that
- span (B)=V span (B)=V.
- BB is linearly independent.
The second condition ensures that all bases of VV will have the same size. In
fact, the dimension of a vector space VV is defined as the number of elements
required in a basis for VV. (Could easily be in infinite.)
- RNRN with BB the “standard basis” for RNRN
{b1,b2,...,bN}=10⋮0,01⋮0,...,00⋮1{b1,b2,...,bN}=10⋮0,01⋮0,...,00⋮1
(1)
Note that this easily extends to ℓp(Z)ℓp(Z).
- RNRN with any set of NN linearly independent vectors
- V={ polynomialsofdegreeatmost p}V={ polynomialsofdegreeatmost p}B={1,t,t2,...,tp}B={1,t,t2,...,tp} (Note that the dimension of VV is p+1p+1)
- V={f(t):f(t) isperiodicwithperiod T}V={f(t):f(t) isperiodicwithperiod T}B={ejkt}k=-∞∞B={ejkt}k=-∞∞ (Fourier series, infinite dimensional)