Formal multilinear series #
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In this file we define formal_multilinear_series π E F to be a family of n-multilinear maps for
all n, designed to model the sequence of derivatives of a function. In other files we use this
notion to define C^n functions (called cont_diff in mathlib) and analytic functions.
Notations #
We use the notation E [Γn]βL[π] F for the space of continuous multilinear maps on E^n with
values in F. This is the space in which the n-th derivative of a function from E to F lives.
Tags #
multilinear, formal series
A formal multilinear series over a field π, from E to F, is given by a family of
multilinear maps from E^n to F for all n.
Equations
- formal_multilinear_series π E F = Ξ (n : β), continuous_multilinear_map π (Ξ» (i : fin n), E) F
Instances for formal_multilinear_series
Equations
Equations
- formal_multilinear_series.module = let _inst : Ξ (n : β), module π (continuous_multilinear_map π (Ξ» (i : fin n), E) F) := Ξ» (n : β), continuous_multilinear_map.module in pi.module β (Ξ» (n : β), continuous_multilinear_map π (Ξ» (i : fin n), E) F) π
Killing the zeroth coefficient in a formal multilinear series
Equations
- p.remove_zero (n + 1) = p (n + 1)
- p.remove_zero 0 = 0
Convenience congruence lemma stating in a dependent setting that, if the arguments to a formal multilinear series are equal, then the values are also equal.
Composing each term pβ in a formal multilinear series with (u, ..., u) where u is a fixed
continuous linear map, gives a new formal multilinear series p.comp_continuous_linear_map u.
Equations
- p.comp_continuous_linear_map u = Ξ» (n : β), (p n).comp_continuous_linear_map (Ξ» (i : fin n), u)
Reinterpret a formal π'-multilinear series as a formal π-multilinear series.
Equations
- formal_multilinear_series.restrict_scalars π p = Ξ» (n : β), continuous_multilinear_map.restrict_scalars π (p n)
Forgetting the zeroth term in a formal multilinear series, and interpreting the following terms
as multilinear maps into E βL[π] F. If p corresponds to the Taylor series of a function, then
p.shift is the Taylor series of the derivative of the function.
Equations
- p.shift = Ξ» (n : β), (p n.succ).curry_right
Adding a zeroth term to a formal multilinear series taking values in E βL[π] F. This
corresponds to starting from a Taylor series for the derivative of a function, and building a Taylor
series for the function itself.
Equations
- q.unshift z (n + 1) = β(continuous_multilinear_curry_right_equiv' π n E F) (q n)
- q.unshift z 0 = β((continuous_multilinear_curry_fin0 π E F).symm) z
Composing each term pβ in a formal multilinear series with a continuous linear map f on the
left gives a new formal multilinear series f.comp_formal_multilinear_series p whose general term
is f β pβ.
Equations
- f.comp_formal_multilinear_series p = Ξ» (n : β), f.comp_continuous_multilinear_map (p n)
The index of the first non-zero coefficient in p (or 0 if all coefficients are zero). This
is the order of the isolated zero of an analytic function f at a point if p is the Taylor
series of f at that point.
Equations
- p.order = has_Inf.Inf {n : β | p n β 0}
The nth coefficient of p when seen as a power series.
The formal counterpart of dslope, corresponding to the expansion of (f z - f 0) / z. If f
has p as a power series, then dslope f has fslope p as a power series.
The formal multilinear series where all terms of positive degree are equal to zero, and the term
of degree zero is c. It is the power series expansion of the constant function equal to c
everywhere.
Equations
- const_formal_multilinear_series π E c n.succ = 0
- const_formal_multilinear_series π E c 0 = continuous_multilinear_map.curry0 π E c