Cannot solve a hyperbolic equation
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Hasan Ghorbani
el 15 de Abr. de 2015
Respondida: Star Strider
el 15 de Abr. de 2015
Hi,
I am trying to solve following equation using Matlab:

And here is my code:
syms z g;
eq1=z*sinh(790*g)==(12.3+i*1.49*10^-3);
eq2=tanh(395g)==z*(1.8*10^-9);
solve(eq1,eq2,z,g)
but I get following error:
Warning: Cannot solve symbolically. Returning a numeric approximation instead.
> In solve at 306
ans =
z: [1x1 sym]
g: [1x1 sym]
What I am doing wrong here?
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Respuesta aceptada
Star Strider
el 15 de Abr. de 2015
For one, you left out a multiplication operator (*) in ‘eq2’. The numeric output is appropriate, since you’re identifying ‘Z0’ and ‘gamma’.
The code (corrected):
syms z g;
eq1=z*sinh(790*g)==(12.3+1i*1.49E-3);
eq2=tanh(395*g)==z*(1.8E-9);
[z,g] = solve(eq1,eq2,z,g)
produces:
z =
58452.259506186817111402883076281 + 3.5404010317307016714429740047407i
g =
0.00000026636472784652195740050195875373 + 0.000000000016133473234585554676003727620685i
Use the vpa or vpasolve functions if you don’t want quite so many digits.
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John D'Errico
el 15 de Abr. de 2015
Why must it be that you did something wrong? Must a symbolic solution exist for all problems? No.
So it gave you a numerical solution. Did you look at what it returned? Does the solution satisfy the equations you have posed?
That was NOT an error anyway, but a warning.
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