JetCalculus[TotalVector] - form the total part of a vector field
Calling Sequences
TotalVector(X)
Parameters
X - a vector field or a generalized vector field on a fiber bundle
Description
Examples
Let π:E→M be a fiber bundle, with base dimension n and fiber dimension m and let πk:JkE → M be the k-th jet bundle with jet coordinates (xi, uα, uiα, uijα, ..., uij ⋅⋅⋅ kα). A total vector field on jet space is a vector field Y of the form Y= AℓDℓ , where the coefficients Aℓ are functions on the jet space JkE and Dℓ is the total vector field for the coordinate xℓ , that is,
Dℓ = ∂∂xℓ + uℓα∂∂uα + uiℓα∂ ∂uiα + uijℓα∂ ∂uijα + ⋅⋅⋅
Total vector fields may be characterized intrinsically as generalized vector fields which annihilate all contact 1-forms. If X = Aℓ ∂ ∂xℓ +Bα ∂ ∂uα is a generalized vector field on E, then the total part is
Xtot = Aℓ ∂∂xℓ + uℓα∂∂uα and the evolutionary part is Xev = Bα −Aℓuℓα∂ ∂uα
The prolongation of Xtot is the total vector field pr(Xtot) = AℓDℓ.
The command TotalVector is part of the DifferentialGeometry:-JetCalculus package. It can be used in the form TotalVector(...) only after executing the commands with(DifferentialGeometry) and with(JetCalculus), but can always be used by executing DifferentialGeometry:-JetCalculus:-TotalVector(...).
with⁡DifferentialGeometry:with⁡JetCalculus:
Example 1.
Create the jet space J2E for the bundle with local coordinates x, y, u, v →x, y. We calculate the total part of some vector fields.
DGsetup⁡x,y,u,v,E,2:
Define a vector X1 and compute its total part.
X1≔evalDG⁡D_x
X1:=D_x
totX1≔TotalVector⁡X1
totX1:=D_x+u1⁢D_u[]+v1⁢D_v[]
The prolongation of tot(X1) is the total derivativewith respect to x.
Prolong⁡totX1,2
D_x+u1⁢D_u[]+v1⁢D_v[]+u1,1⁢D_u1+u1,2⁢D_u2+v1,1⁢D_v1+v1,2⁢D_v2+u1,1,1⁢D_u1,1+u1,1,2⁢D_u1,2+u1,2,2⁢D_u2,2+v1,1,1⁢D_v1,1+v1,1,2⁢D_v1,2+v1,2,2⁢D_v2,2
Define a vector X2 and compute its total part.
X2≔evalDG⁡D_u
X2:=D_u[]
TotalVector⁡X2
0⁢D_x
Define a vector X3 and compute its total part.
X3≔evalDG⁡a⁢D_x+b⁢D_y+c⁢D_u+d⁢D_v
X3:=a⁢D_x+b⁢D_y+c⁢D_u[]+d⁢D_v[]
totX3≔TotalVector⁡X3
totX3:=a⁢D_x+b⁢D_y+b⁢u2+a⁢u1⁢D_u[]+b⁢v2+a⁢v1⁢D_v[]
Example 2.
We show that the total part of a vector field annihilates the 1st order contact forms.
DGsetup⁡x,y,z,u,v,w,J33,3:
X4≔w1,2,3⁢D_z
X4:=w1,2,3⁢D_z
totX4≔TotalVector⁡X4
totX4:=w1,2,3⁢D_z+w1,2,3⁢u3⁢D_u[]+w1,2,3⁢v3⁢D_v[]+w1,2,3⁢w3⁢D_w[]
A total vector field always annihilates the first order contact 1-forms.
ω1≔convert⁡Cu,DGform;ω2≔convert⁡Cv,DGform;ω3≔convert⁡Cw,DGform
ω1:=−u1⁢dx−u2⁢dy−u3⁢dz+du[]
ω2:=−v1⁢dx−v2⁢dy−v3⁢dz+dv[]
ω3:=−w1⁢dx−w2⁢dy−w3⁢dz+dw[]
Hook⁡totX4,ω1,Hook⁡totX4,ω2,Hook⁡totX4,ω3
0,0,0
A vector field is always the sum of its total and evolutionary parts.
evolX4≔EvolutionaryVector⁡X4
evolX4:=−w1,2,3⁢u3⁢D_u[]−w1,2,3⁢v3⁢D_v[]−w1,2,3⁢w3⁢D_w[]
totX4&plusevolX4
w1,2,3⁢D_z
See Also
DifferentialGeometry
JetCalculus
EvolutionaryVector
Hook
Prolong
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