Dear Sage-Developers, I'd like to report two issues that I came across when working with the coding theory classes of SAGE.
1. The Sage Reference Manual: Coding Theory, Release 7.6 [1] explains on p. 31: weight_enumerator [...] This is the bivariate, homogeneous polynomial in 𝑥 and 𝑦 whose coefficient to x^iy^{n-i} is the number of codewords of 𝑠𝑒𝑙𝑓 of Hamming weight 𝑖. Here, 𝑛 is the length of 𝑠𝑒𝑙𝑓. Actually, Sage returns another polynomial, namely the polynomial in 𝑥 and 𝑦 whose coefficient to x^{n-i}y^i is the number of codewords of 𝑠𝑒𝑙𝑓 of Hamming weight 𝑖. (So the roles of x and y are interchanged). This can be directly with C.weight_enumerator?? in the example below [2]. I suggest to either change the description in the reference or to alter the code in Sage. 2. The function weight_enumerator(bivariate=False) returns the evaluation of the the above polynomial for y=1. Should't it be (in the current version) the evaluation with x=1? In other words: Wouldn't one expect a polynomial in x (or y) whose coefficient to x^i (or y^i) is the number of codewords of 𝑠𝑒𝑙𝑓 of Hamming weight 𝑖? The example below [2] illustrates my point: The code has four codewords, one of weight 0, two of weight 3, one of weiht 4. Sage gives x^5 + 2*x^2 + x as the univariate weight enumerator. I would have expected either 1 + 2*x^3 + x^4 or 1 + 2*y^3 + y^4. If you agree, I suggest to alter the code accordingly. Kind regards Barbara PS: I tested the code with Sage version 7.6 on an iMac. [1] http://doc.sagemath.org/pdf/en/reference/coding/coding.pdf [2] Sage code for the SageMathCell C= LinearCode(Matrix(GF(2),2,5, [[1,1,0,1,0], [0,0,1,1,1]])) print C.list() print C.spectrum() print C.weight_enumerator() print C.weight_enumerator(bivariate=False) C.weight_enumerator?? http://sagecell.sagemath.org/?z=eJxztlXwycxLTSxyzk9J1fBNLCnKrNBwd9Mw0tQx0jHVUYiONtQx1DEA4VggzwDMBMLYWE1NXq6Cosy8EgVnvZzM4hINJH5xQWpySVFpLrJYeWpmekZJfGpeaW5qUWJJfhF-yaTMssSizMSSVFu3xJziVKBaLKrs7QGIgD2K&lang=sage -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-devel+unsubscr...@googlegroups.com. To post to this group, send email to sage-devel@googlegroups.com. Visit this group at https://groups.google.com/group/sage-devel. For more options, visit https://groups.google.com/d/optout.