Problem with the function Limit in MATLAB
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Hello, i'm having issues with the function Limit in MATLAB. I put this ecuation y = (x^2 - x - 2)*sqrt(a*x^2 + 1)/(x^2 - a); and then i tryed to do this function:
AHI = limit(y, x, -inf) but when I evaluated that, Matlab answered me with the same question, it answered me this: AHI =
limit(((a*x^2 + 1)^(1/2)*(- x^2 + x + 2))/(- x^2 + a), x, -Inf). Does anyone know what am I doing wrong or how can I solve it? Thank you.
but now I have another problem. With the same ecuation and now typing this, i get an error in another limit. What am I doing wrong in that one?
y = (x^2 - x - 2)*sqrt(a*x^2 + 1)/(x^2 - a);
assume(a, 'Real')
AVI = limit(y, x, a, 'left')
AVI =
((a^3 + 1)^(1/2)*(- a^2 + a + 2))/(- a^2 + a)
采纳的回答
Walter Roberson
2021-3-29
1 个投票
It is having trouble calculating the complex limit.
If you restrict a to real then it has no problem calculating the limit.
5 个评论
Juan Rodríguez
2021-3-29
Walter Roberson
2021-3-29
What error is that? That looks like a reasonable limit
Juan Rodríguez
2021-3-29
Walter Roberson
2021-3-29
That result is obviously wrong, unless a has been assigned something odd.
Consider for example a = 1, so a^2-9 = 1-9 = -8 which is < 0. According to the output shown, the limit should be Inf. So let us look:
x^2-9/x-1 as x approaches 1, does not involve a division by 0 and does not involve infinities. So the limit can be reached through plain substitution: (1)^2-9/1-1 -> 1-9-1 -> -9 . That is not even positive, let alone +infinity.
Juan Rodríguez
2021-3-29
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