This section describes several functions GUAVA uses to manipulate codes. Some of the best codes are obtained by starting with for example a BCH code, and manipulating it.
In some cases, it is faster to perform calculations with a manipulated code than to use the original code. For example, if the dimension of the code is larger than half the word length, it is generally faster to compute the weight distribution by first calculating the weight distribution of the dual code than by directly calculating the weight distribution of the original code. The size of the dual code is smaller in these cases.
Because GUAVA keeps all information in a code record, in some cases the information can be preserved after manipulations. Therefore, computations do not always have to start from scratch.
The next sections describe manipulating function that take a code with certain parameters, modify it in some way and return a different code. See ExtendedCode, PuncturedCode, EvenWeightSubcode, PermutedCode, ExpurgatedCode, AugmentedCode, RemovedElementsCode, AddedElementsCode, ShortenedCode, LengthenedCode, ResidueCode, ConstructionBCode, DualCode, ConversionFieldCode, ConstantWeightSubcode, StandardFormCode and CosetCode.
The next sections describe functions that generate a new code out of two codes. See DirectSumCode, UUVCode, DirectProductCode, IntersectionCode and UnionCode.
GAP 3.4.4