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atlas™ - modern differential geometry for Maple™

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Features List & Examples  |  Introduction  |  Dimension  |  Indexing  |  Forms  |  Metric  |  atlasWizard - Maplet™

atlas[Vectors] - declaration of vectors

Calling Sequence:

     Vectors(V1, V2, ..., Vi, ..., Vn)

Parameters:

       Vi - vector identivier.

Description:

  • In the atlas package any identifier is treated as 0-form  i.e. as non-constant scalar  (if it not declared as constant, p-form, tensor etc. (see atlas[types] )).
  • The Vectors procedure declares vectors. One can declare indexed vectors e.g. E[j] is treated as a set of vectors E[1], E[2], `` .. E[j], `` .. ``  .

Examples:
restart:
with(atlas):

Declare f, h and z as functions:
Vectors(E[j],X,Y,Z,U[i]);

{X, Y, Z, E[j], U[i]}

Verify that E[1] is vector using kind (see atlas[kind] ) and type  procedures:
kind(E[1]);

[1, 0]

type(E[1],vect);

true

Construct new [2,0] tensors T[i,j] using tensor product operator (see atlas[`&.`] ):
T[i,j]:=E[i]&.E[j]+E[j]&.U[i];
'kind(T[i,j])'=kind(T[i,j]);

T[i,j] := `&.`(E[i],E[j])+`&.`(E[j],U[i])

kind(T[i,j]) = [2, 0]

Calculation of Lie derivative (see atlas[L] ):
'L[X]'(f*Z+Y)=L[X](f*Z+Y);

L[X](f*Z+Y) = iota[X](d(f))*Z+f*L[X](Z)+L[X](Y)

Some more examples (see atlas[iota]  and atlas[`&^`] ):
'iota[E[j]](d(x)&^d(y))'=iota[E[j]](d(x)&^d(y));

iota[E[j]](`&^`(d(x),d(y))) = iota[E[j]](d(x))*d(y)-iota[E[j]](d(y))*d(x)

'iota[U[i],Z](d(x)&^d(y))'=iota[U[i],Z](d(x)&^d(y));

iota[U[i],Z](`&^`(d(x),d(y))) = iota[Z](d(x))*iota[U[i]](d(y))-iota[Z](d(y))*iota[U[i]](d(x))

Let's see "who is who"
Who([X,Y,Z,x,E[k],U[1]]);


X: vector

Y: vector

Z: vector

x: 0 - form

E[k]: vector

U[1]: vector


Who();

PIECEWISE([{}, Domains],[{}, Mappings],[{X, Y, Z, E[j], U[i]}, Tensors],[{}, Forms],[{Catalan, _Z, Pi, I, -I}, Constants],[{}, Functions])

See Also:

atlas , atlas[Constants] , atlas[Functions] , atlas[Forms] , atlas[Tensors] , atlas[iota] , atlas[`&^`] , atlas[Who] .