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GAP 4.4 Update 10 (October 2007)

New or improved functionality

  1. Files in the 'cnf' directory of the GAP distribution are now archived as binary files. Now GAP can be installed with UNIX or with WINDOWS style line breaks on any system and should work without problems.
  2. Since large finite fields are available, some restrictions in the code for computing irreducible modules over finite fields are no longer necessary. (They had been introduced in order to give better error messages.)
  3. Made PositionSublist faster in case the search string does not contain repetitive patterns.
  4. The function MakeImmutable now returns its argument.
  5. Dynamically loaded modules now work on Mac OS X. As a consequence, this allows to work with the Browse, EDIM and IO packages on Mac OS X.
  6. Introduced ViewObj and PrintObj methods for algebraic number fields. Made them applicable to AlgebraicExtension by adding the property IsNumberField in the infinite field case.
  7. The function CharacterTableRegular is documented now.
  8. The function ScalarProduct now accepts also Brauer characters as arguments.
  9. The function QuaternionAlgebra now accepts also a list of field elements instead of a field. Also, now the comparison of return values (w.r.t. equality, containment) yields true if the parameters coincide and the ground fields fit.
  10. The function RemoveCharacters is now documented.
  11. Lists in GAP sometimes occupy memory for possible additional entries. Now plain lists and strings read by GAP and the lists returned by List only occupy the memory they really need. For more details see the documentation of the new function EmptyPlist.
  12. There are some new Conway polynomials in characteristic 2 and 3 provided by Kate Minola.
  13. A new operation MemoryUsage determines the memory usage in bytes of an object and all its subobjects. It does not consider families and types but handles arbitrary self-referential structures of objects.

Fixed bugs which could produce wrong results

  1. When forming the semidirect product of a matrix group with a vector space over a non-prime field the embedding of the vector space gave a wrong result. [Reported by anvita21]
  2. DefaultRing failed for constant polynomials over nonprime fields. [Reported by Stefan Kohl]
  3. The method in ffeconway.gi that gets coefficients WRT to the canonical basis of the field from the representation is only correct if the basis is over the prime field. Added a TryNextMethod if this is not the case. [Reported by Alla Detinko]
  4. Creating a large (>2^16) field over a non-prime subfield went completely wrong. [Reported by Jack Schmidt, from Alla Detinko]
  5. A method for Coefficients for Conway polynomial FFEs didn't check that the basis provided was the canonical basis of the RIGHT field. [Reported by BE]
  6. An elementary abelian series was calculated wrongly. [Reported by N. Sieben]
  7. Orbits on sets of transformations failed.
  8. Wrong methods for GeneratorsOfRing and GeneratorsOfRingWithOne have been removed. These methods were based on the assumption that one can obtain a set of ring generators by taking the union of a known set of field generators, the set of the inverses of these field generators and {1}.
  9. The name of a group of order 117600 and degree 50 was incorrect in the Primitive Permutation Groups library. In particular, a group was wrongly labelled as PGL(2, 49).
  10. There was a possible error in `SubgroupsSolvableGroup' when computing subgroups within a subgroup.
  11. An error in 2-Cohomology computation for pc groups was fixed.
  12. `IsConjugate' used normality in a wrong supergroup

Fixed bugs which could lead to crashes

  1. GAP crashed when the PATH environment variable was not set. [Reported by Robert F. Morse]
  2. GAP could crash when started with option -x 1. Now the number of columns is initialized with at least 2. [Reported by Robert F. Morse]
  3. After loading a saved workspace GAP crashed when one tried to slice a compressed vector over a field with 2 < q <= 256 elements, which had already existed in the saved workspace. [Reported by Laurent Bartholdi]
  4. FFECONWAY.WriteOverSmallestCommonField tripped up when the common field is smaller than the field over which some of the vector elements are written, because it did a test based on the degree of the element, not the field it is written over. [Reported by TB]
  5. Fixed the following error: When an FFE in the Conway polynomial representation actually lied in a field that is handled in the internal representation (eg GF(3)) and you tried to write it over a bigger field that is ALSO handled internally (eg GF(9)) you got an element written over the larger field, but in the Conway polynomial representation, which is forbidden. [Reported by Jack Schmidt]
  6. Attempting to compress a vector containing elements of a small finite field represented as elements of a bigger (external) field caused a segfault. [Reported by Edmund Robertson]
  7. GAP crashed when BlistList was called with a range and a list containing large integers or non-integers. [Reported by Laurent Bartholdi]
  8. GAP no longer crashes when OnTuples is called with a list that contains holes. [Reported by TB]

Other fixed bugs

  1. `Socle' for the trivial group could produce an error message.
  2. DirectoryContents ran into an error for immutable strings without trailing slash as argument. [Reported by TB]
  3. The functions IsInjective and IsSingleValued did not work for general linear mappings with trivial (pre)image. [Reported by Alper Odabas]
  4. Creating an enumerator for a prime field with more than 65536 elements ran into an infinite recursion. [Reported by Akos Seress]
  5. The performance of List, Filtered, Number, ForAll, and ForAny if applied to non-internally represented lists was improved. Also the performance of iterators for lists was slightly improved.
  6. Finite field elements now know that they can be sorted easily which improves performance in certain lookups.
  7. A method for IsSubset was missing for the case that exactly one argument is an inhomogeneous list. [Reported by Laurent Bartholdi]
  8. Long integers in expressions are now printed (was not yet implemented). [Reported by TB]
  9. Fixed kernel function for printing records.
  10. New C library interfaces (e.g., to ncurses in Browse) need some more memory to be allocated with 'malloc'. The default value of GAPs '-a' option is now '2m'.
  11. Avoid warnings about pointer types by newer gcc compilers.
  12. IsBound(l[pos]) was failing for large integer <pos> only when coded (eg in a loop or function body).
  13. ZmodpZObj is now a synonym for ZmodnZObj such that from now on such objects print in a way that can be read back into GAP.
  14. The outdated note that binary streams are not yet implemented has been removed.