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Trying to plot with complex quantities seems not to work properly in what I want to accomplish. I would like to know if there is a general rule/way of plotting when you have complex counterparts in your function. I tried looking up `ContourPlot`

and `DensityPlot`

but I only have one single variable as `ContourPlot`

asks for two variables in order to plot. The expression I am trying to plot is as so:

```
eqn := (25 Pi f I)/(1 + 10 Pi f I)
Plot[eqn,{f,-5,5}]
```

If there something else that is missing here?

`Plot`

displays $\mathbb{R}\to\mathbb{R}$ functions. How is it supposed to interpret`I`

? – rcollyer – 2012-03-25T01:25:31.217Is your variable

`f`

supposed to be just real (as suggested by the domain in your`Plot`

expression)? Or do you want it to take more general complex values, too? – murray – 2012-03-25T16:45:36.060@murray: Well the function

`f`

is complex valued. It reads as`G(f) = (25 Pi f I) / (1 + 10 Pi f I)`

. So, what I was trying to accomplish is plot the spectrum or "Fourier Transform (frequency response)", of the function $g(t)$. Where $f$ just represent the frequency variable from the time-domain. I hope that makes sense to clear up your question. – night owl – 2012-03-26T00:07:58.883@night owl: a typical communication between a mathematician and a non-matthematician? (I think of a complex-valued function of a real variable; you speak about respone of frequency.) But I understand! You do have a function from the real numbers to the complex numbers, so the way to represent it visually is unclear. For things like density plots and contour plots, one is dealing with a domain consisting of pairs of reals or, equivalently,complex numbers and range real numbers. Your situation is precisely the reverse. – murray – 2012-03-26T03:55:27.730

@murray: Edit: I meant to say the function

`G`

is complex, but can be seen from above. – night owl – 2012-03-26T04:45:55.013@night owl: Stating "the function

`G`

is complex" is ambiguous. What is its domain? (just reals or all complex numbers?) Clearly its codomain is the complex numbers. – murray – 2012-03-26T14:04:05.143