Hi Ralf, On 2018-03-28, Ralf Stephan <gtrw...@gmail.com> wrote: > Ask yourself, are these arguments you give for current is_prime(x) > behaviour not just the inertia of your thinking.
No. It is a sign of appreciation of mathematical notions. Sorry to start with politics here, but I am against populism. And dropping mathematical rigor in order to get more votes (i.e., more users), just because of some guess that a large proportion of potential users of maths software might refuse to start learning about mathematical notions, *is* populism, IMHO. Also, that attitude is a grave indectment against once own educational capacity. Instead, I would strive to improve mathematical knowledge of the users. Not by letting the user fall into the pitfalls of maths, but by pointing the users to such pitfalls (warning messages etc.). > Wolfram tells me plainly "1/3 (2^23 + 1) is a prime number"---no ambiguity, > no attempt to show a glimpse of algebraic truth. Shame on Wolfram. It's the same problem that results from using calculators in school: Many of my students are uncomfortable with fractions, will even not simplify 5/10 to 1/2, and will convert 1/4 into 0.25. As a consequence, they fail tests at university, as they are designed to be easily solvable with exact computations using paper and pen (I am just grading such exam). > But then it's clear that the value is not integer: > In [8]: (2**23+1)/3 > Out[8]: 2796203.0 As I said in an earlier post, I'd be in favour of changing printed output of basic number types in Sage, so that pasting output will result in a copy of the object. > Why not improve mathematics? Why not define the primality term you apply in > the element is_prime() as having a different name than "prime"? Why not > introduce 123/1 as notation to avoid ambiguities in mathematics? I'm quite > astonished that mathematicians allow these fuzziness in their language, it > is unusual. It is not mathematicians being fuzzy, but it is the interplay of mathematical notions and (unintended?) implications of computations. Namely, when the user writes x=3/1, she implies that x shall be considered as an element of QQ, and Sage keeps track of that implication. And then, there is a clear mathematical notion of primality, which means that there are no primes in QQ. Best regards, Simon -- 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.
