2019-09-05 19:54:36 +0100 received badge ● Popular Question (source) 2014-07-21 17:49:52 +0100 answered a question Any way to get numeric result of part of symbolic expresssion? Hello, I would try n(sqrt(2)) + x. This results in x + 1.41421356237310 2014-07-21 15:35:27 +0100 commented answer Create an infinite set with list comprehension Another remark: a 'generator' object has no attribute 'cardinality'. So if I want to work with this, I am getting the error "'generator' object has no attribute 'cardinality'". This was another reason I wanted to work with sets. 2014-07-21 15:30:52 +0100 commented answer Create an infinite set with list comprehension Hello, thank you for the answer. The reason for using Set was, that I wanted to operate with Sage sets. I wanted to do some set theory operations like union or difference of two sets. I thought the members of an operation like A = Set(B.difference(C)) should be all the same type. Thank you. Vasile 2014-07-21 10:12:46 +0100 asked a question Create an infinite set with list comprehension Hello. In Sage is possible to create B = Set(Primes()). For B Sage says Set of all prime numbers: 2, 3, 5, 7, ... . So B is infinite. I try to create now a set C = Set([x^2 for x in QQ]). I am expecting to get something similar like above, but Sage does not get so far. After some 20 Minutes of waiting I broke down the action. Is possible to create an infinite Set with list comprehension? I know that lists should befinite but the notation used by list comprehension is very near on the mathematical way to describe a set like D = Set([x^2 for x in range(10)]) for example. Any help appreciated. Thank you and regards, Vasile 2014-07-21 08:42:06 +0100 commented answer How th work with enumerable and infinite set Thank you for the reply. vbk 2014-07-18 15:51:01 +0100 asked a question How th work with enumerable and infinite set Hello, I am trying to do following: construct the set B that is the difference between QQ and the set of the prime numbers (note that B is a countable set). Within Sage, I tried the following X = Set(QQ) Y = Set(Primes()) B = Set(X.difference(Y)) B.cardinality()  then I press evaluate. I am expecting that the cardinality of B is +Infinity. But Sage does not bring any result. I tried this also initializing B like B = InfiniteEnumeratedSets(RR).  Could anybody please give me a hint what I am doing wrong? Thank you very much and regards. vbk