Unable to find explicit solution

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Tiku
Tiku 2021-4-1
评论： Tiku 2021-4-4
Matlab says "Unable to find explicit solution" when trying to solve following non linear equation
-log(y) = psi(1/2+ x/y) - psi(1/2)
Here psi is digamma function
What is wrong with my code, below?
I am using matlab version R2021a
syms x y
eqn = psi(1/2 + x/y)- psi(1/2)+ log(y)==0;
soly = solve(eqn,y)
Warning:
Unable to find explicit solution. For options, see help.
> In sym/solve (line 317)
soly =
Empty sym: 0-by-1
  2 个评论
Matt J
Matt J 2021-4-1
It seems very plausible to me that an explicit solution does not exist. Do you have reason to think otherwise?
Tiku
Tiku 2021-4-1
Thank you for the reply.
I see explicit solution doesn't exist.
That means in order to plot y vs x I should assigned the value of x and solve for y right?

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采纳的回答

Matt J
Matt J 2021-4-1
You can use fimplicit.
  9 个评论
显示 7更早的评论
Matt J
Matt J 2021-4-2
We've no reason to trust the paper more than Matlab...
Tiku
Tiku 2021-4-4
I totally agree Matlab calulation is right. Actually after the plot I have to use some physics to ignore certain parts of the plot so at this stage both Matlab and paper is right.
So I really apppreciate your help and thank you.

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