Changeset b4a463 in git
- Timestamp:
- Jul 18, 2006, 2:17:36 PM (18 years ago)
- Branches:
- (u'spielwiese', 'fe61d9c35bf7c61f2b6cbf1b56e25e2f08d536cc')
- Children:
- c89c574998a1ffa7816eb2b5e388287e16b1a4b0
- Parents:
- f04aafa3db2b15cf551661055b7cfbce72c3d342
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- 1 edited
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Singular/LIB/ainvar.lib
rf04aaf rb4a463 1 // $Id: ainvar.lib,v 1. 7 2002-04-12 16:19:41Singular Exp $1 // $Id: ainvar.lib,v 1.8 2006-07-18 12:17:36 Singular Exp $ 2 2 ///////////////////////////////////////////////////////////////////////////// 3 version="$Id: ainvar.lib,v 1. 7 2002-04-12 16:19:41Singular Exp $";3 version="$Id: ainvar.lib,v 1.8 2006-07-18 12:17:36 Singular Exp $"; 4 4 category="Invariant theory"; 5 5 info=" … … 62 62 proc derivate (matrix m, id) 63 63 "USAGE: derivate(m,id); m matrix, id poly/vector/ideal 64 ASSUME: m is a nx1 matrix, where n = number of variables of the basering64 ASSUME: m is an nx1 matrix, where n = number of variables of the basering 65 65 RETURN: poly/vector/ideal (same type as input), result of applying the 66 66 vector field by the matrix m componentwise to id; … … 274 274 proc completeReduction(poly p, ideal dom, list #) 275 275 "USAGE: completeReduction(p,I[,q,n]); p poly, I ideal, [q monomial, n int] 276 RETURN: a polynomial, the SAGBI reduction of the polynomial p with I276 RETURN: a polynomial, the SAGBI reduction of the polynomial p with respect to I 277 277 via the procedure 'reduction' as long as possible 278 278 if n=1, a different algorithm is chosen which is sometimes faster … … 338 338 @end format 339 339 with respect to p,q,h. It is defined as follows: set inv = p if p is 340 invariant, and else as340 invariant, and else set 341 341 inv = m(q)^N * sum_i=1..N-1{ (-1)^i*(1/i!)*m^i(p)*(q/m(q))^i } 342 where m^N(p) = 0, m^(N-1)(p) != 0; 343 the result is inv divided by h as muchas possible342 where m^N(p) = 0, m^(N-1)(p) != 0; the result is inv divided by h 343 as often as possible 344 344 EXAMPLE: example localInvar; shows an example 345 345 " … … 405 405 @end format 406 406 i.e. we compute elements in the (invariant) subring generated by id 407 which are divisible by q and divide them by q as much as possible408 the second ideal contains all invariants given before409 if n=1, a different algorithm is chosen which is sometimes faster407 which are divisible by q and divide them by q as often as possible. 408 The second ideal contains all invariants given before. 409 If n=1, a different algorithm is chosen which is sometimes faster 410 410 (default: n=0) 411 411 EXAMPLE: example furtherInvar; shows an example … … 508 508 If b<=0, the computation continues until all generators 509 509 of the ring of invariants are computed (should be used only if the 510 ring of invariants is known to be finitely generated otherwise the510 ring of invariants is known to be finitely generated, otherwise the 511 511 algorithm might not stop). 512 512 If r=1 a different reduction is used which is sometimes faster … … 514 514 DISPLAY: if pa is given (any string as 5th or 6th argument), the computation 515 515 pauses whenever new invariants are found and displays them 516 THEORY: The algorithm to compute the ring of invariants works in char 0 517 or big enough characteristic. (K,+) acts as the exponential of the 518 vector field defined by the matrix m. For background see G.-M. Greuel, 519 G. Pfister, Geometric quotients of unipotent group actions, Proc. 516 THEORY: The algorithm for computing the ring of invariants works in char 0 517 or suffiently large characteristic. 518 (K,+) acts as the exponential of the vector field defined by the 519 matrix m. 520 For background see G.-M. Greuel, G. Pfister, 521 Geometric quotients of unipotent group actions, Proc. 520 522 London Math. Soc. (3) 67, 75-105 (1993). 521 523 EXAMPLE: example invariantRing; shows an example
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