Problem to solve exponential equation

2018 4 13
2 个回答
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更新时间：2018 4 14
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1 个投票

hello. I have a problem when a try solve exp(1/x)=b equation where b is a known number. for example vpasolve(exp(1/x)==3,x) the result is -1.0787658120660760897089735826813e186744862 that's clearly wrong. please help me

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Walter Roberson
Walter Roberson 2018-4-13
编辑：Walter Roberson 2018-4-13

0 个投票

You are right, I am seeing the same thing, but different results.
-2.9994493695148696857379250512264623387666217934763e178433142
I will file a bug report... filed.

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James Tursa
James Tursa 2018-4-13
编辑：James Tursa 2018-4-13

0 个投票

Why not solve it directly:
x = 1./log(b)
What's the point of using vpasolve for this?

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Jose Fernandez
Jose Fernandez 2018-4-14
because the equation that i want solve is exp(-(3.14*ra)/x)+exp(-(3.14*rb)/x)=1 and in this case i cant apply log to solve. but i realize a change of variable x=1/y to solve getting good results. thanks

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