"Cannot find explicit solution"

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Ill ch 2019-10-13

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https://ww2.mathworks.cn/matlabcentral/answers/485000-cannot-find-explicit-solution

评论： Walter Roberson 2019-10-15

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Dear Matlab users,

Matlab says "Cannot find explicit solution" . Can anybody solve my problem?

syms A delta phi w w0 Tmax Yf
eqn = Yf ==(A*(delta*cos(phi) + w0*sin(phi) + w*cos(phi)*1i))/(delta^2 + delta*w*2i - w^2 + w0^2) + (A*exp(-Tmax*delta)*(sin(Tmax*w) + cos(Tmax*w)*1i)*(delta*cos(phi - Tmax*w0) + w*cos(phi - Tmax*w0)*1i + w0*sin(phi - Tmax*w0))*1i)/(delta^2 + delta*w*2i - w^2 + w0^2)
 
sol_4=solve(eqn,Tmax)
sol_1=solve(eqn,A)
sol__2=solve(eqn,delta)
sol_3=solve(eqn,w0)
Warning: Unable to find explicit solution. For options, see help. 
> In solve (line 317) 

Thank you

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darova 2019-10-15

I don't know :(

Walter Roberson 2019-10-15

This is not a simple (A+B)/C equation. Tmax occurs in multiple trig terms, some of which are in connection with imaginary components, and some of which involve phase . It is unlikely that there is a closed form solution for Tmax.

A is the only variable there is reasonably a closed form solution for.

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