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Why does Maple evaluate the first limit but not the second:

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xoux
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    The second doesn't exist. – PinkyWay Apr 24 '22 at 05:28
  • Okay, but am I missing something regarding the user interface here? Why doesn't Maple give some kind of indication of this fact. – xoux Apr 24 '22 at 05:30
  • Why don't use MathJax for the write the question? – A. P. Apr 24 '22 at 05:38
  • I really wonder why pretty much every single question I have ever asked about Maple is downvoted, and when I go through the tag "maple", pretty much every question is downvoted. This is least receptive tag to questions that I have seen on any of the stack exchange websites. 12 downvoted questions, 5 upvoted questions, and 12 questions with no votes. These are the 29 first questions with the maple tag that I see. – xoux Apr 24 '22 at 05:46
  • Are people not supposed to ask any questions about maple? I use Maple to solve mathematical problems, and in the course of doing so I usually encounter some aspect of using Maple to solve a mathematical problem that I don't understand. "For questions involving the application of the program Maple to mathematics". This is literally what I am doing by using Maple and then asking a question. – xoux Apr 24 '22 at 05:46
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    I cant answer for others questions but I would say that yours lacks your personnal thoughts. It is a valid motive for a downvote. – nicomezi Apr 24 '22 at 05:53
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    Actually your question here is quite clearly about Maple and not mathematics: you're asking why Maple behaves in a certain way. You should ask about Maple's behaviour on a forum for Maple. If your question were about how to use Maple to evaluate one-sided limits then you'd be on much safer ground here. – postmortes Apr 24 '22 at 06:34

1 Answers1

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Maple doesn't have a way to indicate a limit that is $+\infty$ from one side and $-\infty$ from the other. You might try

> limit(a*x^2/(2*x-a),x=a/2, right) assuming a > 0;

$$ \infty $$

> limit(a*x^2/(2*x-a),x=a/2, left) assuming a > 0;

$$-\infty $$

Robert Israel
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  • Is there some mathematical ambiguity that prevents indicating that the limits from above and below are different? I am just wondering if I am missing some minutiae since at first glance it would seem to be a simple UI issue to do something other than echo back the limit as it was written by the user. – xoux Apr 24 '22 at 19:26
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    When Maple returns the limit unevaluated, it means either that the limit doesn't exist or that Maple can't find it. Perhaps there is more that can be said about it, but Maple is answering the question that was asked. There are many ways that a limit might not exist, and having different one-sided limits from left and right is only one of them. You might treat Maple's response as an invitation to find out more about the limiting behaviour of this function by trying other commands (such as the one-sided limits). – Robert Israel Apr 25 '22 at 05:14