Finsupp.linearCombination
#
Main definitions #
Finsupp.linearCombination R (v : ι → M)
: sendsl : ι → R
to the linear combination ofv i
with coefficientsl i
;Finsupp.linearCombinationOn
: a restricted version ofFinsupp.linearCombination
with domain
Tags #
function with finite support, module, linear algebra
Interprets (l : α →₀ R) as a linear combination of the elements in the family (v : α → M) and evaluates this linear combination.
Equations
- Finsupp.linearCombination R v = (Finsupp.lsum ℕ) fun (i : α) => LinearMap.id.smulRight (v i)
Instances For
Alias of Finsupp.linearCombination
.
Interprets (l : α →₀ R) as a linear combination of the elements in the family (v : α → M) and evaluates this linear combination.
Equations
Instances For
Alias of Finsupp.linearCombination_apply
.
Alias of Finsupp.linearCombination_single
.
Alias of Finsupp.linearCombination_zero_apply
.
Alias of Finsupp.linearCombination_zero
.
Alias of Finsupp.apply_linearCombination
.
Alias of Finsupp.apply_linearCombination_id
.
Alias of Finsupp.linearCombination_unique
.
Alias of Finsupp.linearCombination_surjective
.
Alias of Finsupp.linearCombination_range
.
Any module is a quotient of a free module. This is stated as surjectivity of
Finsupp.linearCombination R id : (M →₀ R) →ₗ[R] M
.
Alias of Finsupp.linearCombination_id_surjective
.
Any module is a quotient of a free module. This is stated as surjectivity of
Finsupp.linearCombination R id : (M →₀ R) →ₗ[R] M
.
Alias of Finsupp.range_linearCombination
.
Alias of Finsupp.lmapDomain_linearCombination
.
Alias of Finsupp.linearCombination_embDomain
.
Alias of Finsupp.linearCombination_mapDomain
.
Alias of Finsupp.linearCombination_equivMapDomain
.
A version of Finsupp.range_linearCombination
which is useful for going in the other
direction
Alias of Finsupp.span_eq_range_linearCombination
.
A version of Finsupp.range_linearCombination
which is useful for going in the other
direction
Alias of Finsupp.mem_span_iff_linearCombination
.
Alias of Finsupp.linearCombination_option
.
Alias of Finsupp.linearCombination_fin_zero
.
Finsupp.linearCombinationOn M v s
interprets p : α →₀ R
as a linear combination of a
subset of the vectors in v
, mapping it to the span of those vectors.
The subset is indicated by a set s : Set α
of indices.
Equations
- Finsupp.linearCombinationOn α M R v s = LinearMap.codRestrict (Submodule.span R (v '' s)) (Finsupp.linearCombination R v ∘ₗ (Finsupp.supported R R s).subtype) ⋯
Instances For
Alias of Finsupp.linearCombinationOn
.
Finsupp.linearCombinationOn M v s
interprets p : α →₀ R
as a linear combination of a
subset of the vectors in v
, mapping it to the span of those vectors.
The subset is indicated by a set s : Set α
of indices.
Equations
Instances For
Alias of Finsupp.linearCombinationOn_range
.
Alias of Finsupp.linearCombination_comp
.
Alias of Finsupp.linearCombination_comapDomain
.
Alias of Finsupp.linearCombination_onFinset
.
Fintype.linearCombination R S v f
is the linear combination of vectors in v
with weights
in f
. This variant of Finsupp.linearCombination
is defined on fintype indexed vectors.
This map is linear in v
if R
is commutative, and always linear in f
.
See note [bundled maps over different rings] for why separate R
and S
semirings are used.
Equations
- Fintype.linearCombination R S = { toFun := fun (v : α → M) => { toFun := fun (f : α → R) => ∑ i : α, f i • v i, map_add' := ⋯, map_smul' := ⋯ }, map_add' := ⋯, map_smul' := ⋯ }
Instances For
Alias of Fintype.linearCombination
.
Fintype.linearCombination R S v f
is the linear combination of vectors in v
with weights
in f
. This variant of Finsupp.linearCombination
is defined on fintype indexed vectors.
This map is linear in v
if R
is commutative, and always linear in f
.
See note [bundled maps over different rings] for why separate R
and S
semirings are used.
Equations
Instances For
Alias of Fintype.linearCombination_apply
.
Alias of Fintype.linearCombination_apply_single
.
Alias of Finsupp.linearCombination_eq_fintype_linearCombination_apply
.
Alias of Finsupp.linearCombination_eq_fintype_linearCombination
.
Alias of Fintype.range_linearCombination
.
An element x
lies in the span of v
iff it can be written as sum ∑ cᵢ • vᵢ = x
.
A family v : α → V
is generating V
iff every element (x : V)
can be written as sum ∑ cᵢ • vᵢ = x
.
Pick some representation of x : span R w
as a linear combination in w
,
((Finsupp.mem_span_iff_linearCombination _ _ _).mp x.2).choose
Instances For
Alias of Span.finsupp_linearCombination_repr
.
Alias of LinearMap.map_finsupp_linearCombination
.
An element m ∈ M
is contained in the R
-submodule spanned by a set s ⊆ M
, if and only if
m
can be written as a finite R
-linear combination of elements of s
.
The implementation uses Finsupp.sum
.
An element m ∈ M
is contained in the R
-submodule spanned by a set s ⊆ M
, if and only if
m
can be written as a finite R
-linear combination of elements of s
.
The implementation uses a sum indexed by Fin n
for some n
.
The span of a subset s
is the union over all n
of the set of linear combinations of at most
n
terms belonging to s
.