| atlas[`&^`] - exterior product operator Calling Sequence: `&^`(F1,F2, ..., Fn) F1 &^ F2 Parameters: F1, F2, ..., Fn - forms. Description: - The &^ procedure calculates the exterior product of given forms. The main syntax is as follows: omega[1]&^omega[2] i.e.
where and are forms. To calculate exterior product for forms use the following `&^`(omega[1],omega[2], ...omega[k]) i.e. ![`&^`(omega[1],omega[2],`` .. omega[k])](prod/atlas/help/images/wedge5.gif) - Exterior product is linear operation with respect to its arguments. Thus if
are 0-forms then: ![`&^`(omega[1],alpha*omega[2]+beta*omega[3]) = alpha*`&^`(omega[1],omega[2])+beta*`&^`(omega[1],omega[3])](prod/atlas/help/images/wedge7.gif) - Let
be p-form and be q-form then the following formula for exterior product takes place: - Particularly for 1-forms
and we have: 
Examples: restart: with(atlas): Declare p-forms: Forms(sigma=1,omega=1,omega[1]=p,omega[2]=q,omega[3]=l); ![{sigma, omega, omega[1], omega[2], omega[3]}](prod/atlas/help/images/wedge14.gif)
Declare vectors: Vectors(X,Y,Z); 
Using &^ - procedure: Exterior product is linear operation with respect to its arguments '`&^`(omega[1],alpha*omega[2]+beta*omega[3])' = `&^`(omega[1],alpha*omega[2]+beta*omega[3]); ![`&^`(omega[1],alpha*omega[2]+beta*omega[3]) = alpha*`&^`(omega[1],omega[2])+beta*`&^`(omega[1],omega[3])](prod/atlas/help/images/wedge16.gif)
As is p-form and is q-form then under main rule for exterior product we have: 'omega[2]&^omega[1]'=omega[2]&^omega[1]; ![`&^`(omega[2],omega[1]) = (-1)^(q*p)*`&^`(omega[1],omega[2])](prod/atlas/help/images/wedge19.gif)
Particularly for 1-forms and we have: 'sigma&^omega'=sigma&^omega; 
Some more examples: '`&^`(omega,sigma,omega[3],omega[2],omega[1])' = `&^`(omega,sigma,omega[3],omega[2],omega[1]); ![`&^`(omega,sigma,omega[3],omega[2],omega[1]) = (-1)^(1+(q+l)*p+l*q)*`&^`(sigma,omega,omega[1],omega[2],omega[3])](prod/atlas/help/images/wedge23.gif)
And with Lie derivative: 'L[X]'(omega&^sigma)=L[X](omega&^sigma); ) = -`&^`(sigma,iota[X](d(omega)))-`&^`(sigma,d(iota[X](omega)))+`&^`(omega,iota[X](d(sigma)))+`&^`(omega,d(iota[X](sigma)))](prod/atlas/help/images/wedge24.gif)
And with exterior derivative: 'd'(omega&^sigma)=d(omega&^sigma); 
And again 'L[X]'(omega[1])=L[X](omega[1]);  = iota[X](d(omega[1]))+d(iota[X](omega[1]))](prod/atlas/help/images/wedge26.gif)
And finally 'omega[3]&^(L[Z](omega)&^sigma)'=omega[3]&^(L[Z](omega)&^sigma); ![`&^`(omega[3],`&^`(L[Z](omega),sigma)) = -(-1)^l*`&^`(sigma,omega[3],iota[Z](d(omega)))-(-1)^l*`&^`(sigma,omega[3],d(iota[Z](omega)))](prod/atlas/help/images/wedge27.gif)
See Also: atlas , atlas[L] , atlas[d] , atlas[`&.`] , atlas[Forms] . |