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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

Description

• 

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(...).

Examples

> 

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.

E > 

X1≔evalDG⁡D_x

X1:=D_x

(2.1)
E > 

totX1≔TotalVector⁡X1

totX1:=D_x+u1⁢D_u[]+v1⁢D_v[]

(2.2)

 

The prolongation of tot(X1) is the total derivative with respect to x.

E > 

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

(2.3)

 

Define a vector X2 and compute its total part.

E > 

X2≔evalDG⁡D_u

X2:=D_u[]

(2.4)
E > 

TotalVector⁡X2

0⁢D_x

(2.5)

 

Define a vector X3 and compute its total part.

E > 

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[]

(2.6)
E > 

totX3≔TotalVector⁡X3

totX3:=a⁢D_x+b⁢D_y+b⁢u2+a⁢u1⁢D_u[]+b⁢v2+a⁢v1⁢D_v[]

(2.7)

 

Example 2.

We show that the total part of a vector field annihilates the 1st order contact forms.

E > 

DGsetup⁡x,y,z,u,v,w,J33,3:

J33 > 

X4≔w1,2,3⁢D_z

X4:=w1,2,3⁢D_z

(2.8)
J33 > 

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[]

(2.9)

 

A total vector field always annihilates the first order contact 1-forms.

J33 > 

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[]

(2.10)
J33 > 

Hook⁡totX4,ω1,Hook⁡totX4,ω2,Hook⁡totX4,ω3

0,0,0

(2.11)

 

A vector field is always the sum of its total and evolutionary parts.

J33 > 

evolX4≔EvolutionaryVector⁡X4

evolX4:=−w1,2,3⁢u3⁢D_u[]−w1,2,3⁢v3⁢D_v[]−w1,2,3⁢w3⁢D_w[]

(2.12)
J33 > 

totX4&plusevolX4

w1,2,3⁢D_z

(2.13)

See Also

DifferentialGeometry

JetCalculus

EvolutionaryVector

Hook

Prolong