Cannot solve a hyperbolic equation

조회 수: 2 (최근 30일)
Hasan Ghorbani
Hasan Ghorbani 2015년 4월 15일
답변: Star Strider 2015년 4월 15일
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?

채택된 답변

Star Strider
Star Strider 2015년 4월 15일
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.

추가 답변 (1개)

John D'Errico
John D'Errico 2015년 4월 15일
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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