problem with calculation limit

2015 3 25
1 个回答
更新时间：2015 3 25
2 次查看（30 天）

0 个投票

Hi, I have recently used matlab to calculate the limit of the following function when E goes to minus infinity:
-E*(log(1/(exp(3*E) + 1))/(exp(3*E) + 1) - log(1/(exp(3*E + 3*a) + 1))/(exp(3*E + 3*a) + 1))
But Matlab returns:
limit(-E*(log(1/(exp(3*E) + 1))/(exp(3*E) + 1) - log(1/(exp(3*E + 3*a) + 1))/(exp(3*E + 3*a) + 1)), E == -Inf)
Does anybody knows what is going on? Am I doing something wrong?

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回答（1 个）

Roger Stafford
Roger Stafford 2015-3-25
编辑：Roger Stafford 2015-3-25

0 个投票

I would think the limit is zero by L'Hospital's rule, but it is possible that matlab's 'limit' function either doesn't know how to determine that or else it objects to the presence of the unknown variable 'a'. Try giving 'a' a specific value and see how it performs.

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