how can we plot it ?

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8167 2013-10-17

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回答： David Sanchez 2013-10-17

equation = -0.4787 + 7.3246 * (3.14 * 0.05/x) +0.3963 * (3.14 * 0.05/x)^2 + 15.613 * (3.14 * 0.05/x)^3 +(1j * (266.265 * cot (0.05 * 3.14/x)- .4456 +17.0082 * (0.05 * 3.14/x)- 8.6793 * ((0.05 * 3.14/x)^2) + 9.60131 * ((0.05 * 3.14/x)^3)) =144.3
i need to plot frequency which is 
f= 3*10^8/x

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Walter Roberson 2013-10-17

Is the "1j" intended to represent the imaginary constant? If so then is x itself intended to be a complex number, or is it expected that the imaginary portion will resolve to be 0 ?

8167 2013-10-17

在 MATLAB Online 中打开

and what if we ignore the ij and put the equation 
-0.4787 + 7.3246 * (3.14 * 0.05/x) +0.3963 * (3.14 * 0.05/x)^2 + 15.613 * (3.14 * 0.05/x)^3 +((266.265 * cot (0.05 * 3.14/x)- .4456 +17.0082 * (0.05 * 3.14/x)- 8.6793 * ((0.05 * 3.14/x)^2) + 9.60131 * ((0.05 * 3.14/x)^3)) =144.3
f= 3*10^8/x

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Answer 1

Walter Roberson 2013-10-17

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If the "1j" is intended to represent the imaginary constant, then the equation has no real-valued solutions. The real part of the equation has a singularity at x = 0, at which it switches from always negative to always positive, no zero crossing.

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8167 2013-10-17

yeah so can we plot it ?

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Answer 2

David Sanchez 2013-10-17

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You can not plot it. The lay out of your problem is not right. Your equation has zero crossing (=solution)according to Walter Roberson. What are you going to plot against what?