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D.15.2.34 derivationToString

Procedure from library difform.lib (see difform_lib).

Usage:
derivationToString(phi,#); phi derivation, # list

Return:
the derivation as a string, describing the image of the degree-1 generators, optionally ordered by a given monomial ordering on the generators

Remarks:
To sort the images of the generators in the output string, difformListSort is used.

Note:
to define an ordering for the generators, one can use:
- #[1] = 'gen'
- #[2]: a monomial ordering as string
- #[3]: an optional weight vector
the standard ordering is the ordering of the differential algebra

Example:
 
LIB "difform.lib";
ring R = 0,(x,y,z),dp;
diffAlgebra();
==> // The differential algebra Omega_R was constructed and the differential \
   forms dDx, dDy, dDz, dx, dy, dz are available.
list L; L[1] = list(dx,dy,dz); L[2] = list(x2,y-23xz,xz4);
derivation phi = L;
///////////////////////////////////
// String with standard ordering //
///////////////////////////////////
print(derivationToString(phi));
==>  Omega_R^1 --> R
==>        dz |--> xz4
==>        dy |--> -23xz+y
==>        dx |--> x2
==> 
//////////////////////////////////
// String with changed ordering //
//////////////////////////////////
print(derivationToString(phi,"gen","wp",intvec(-1,-1,1)));
==>  Omega_R^1 --> R
==>        dy |--> -23xz+y
==>        dx |--> x2
==>        dz |--> xz4
==> 
kill Omega_R,dx,dy,dz,L,phi;
See also: derivationPrint; difformGenToString; difformListSort.


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