       Re: Plot problem

• To: mathgroup at smc.vnet.net
• Subject: [mg3612] Re: Plot problem
• From: ianc (Ian Collier)
• Date: Thu, 28 Mar 1996 00:10:35 -0500
• Organization: Wolfram Research, Inc.
• Sender: owner-wri-mathgroup at wolfram.com

```In article <4j7hbd\$af4 at dragonfly.wolfram.com>, Pierluigi Puccetti
<puccetti at sienanet.it> wrote:

> Chiara Mocenni Puccetti
> Universita' di Siena - ITALY
>
> f[t_]:=(22.39638707132903 - 38.3879329433359*I)*E^((-0.005 -
> 0.999987499921874*I)*t) +
>
>   (7.912734995684308 - 0.5556111312856052*I)*Cos[1.1*t] +
>
>   (-17.89146077765513 + 1.146859050666162*I)*Sin[1.1*t];
>
> This function is the solutin
> on (obtained with DSolve) of a system of two differential equations.
> There are complex numbers,
> and I am enable to plot this functions in the time variable.
> I am not yet really expert, there is someone that can help me ?
>
> Thanks you
>
> Chiara

Mathematica's plotting functions are only able to plot
quantities that evaluate to real numbers.

In this case you can plot either the real or imaginary
parts of the function - or you can plot one against the
other using ParametricPlot.

Here are some examples:

In:=
f[t_]:=(22.39638707132903 - 38.3879329433359*I)*
E^((-0.005 - 0.999987499921874*I)*t) +
(7.912734995684308 - 0.5556111312856052*I)*Cos[1.1*t] +
(-17.89146077765513 + 1.146859050666162*I)*Sin[1.1*t];

In:=
Plot[ Re[ f[t] ], {t,-10,10}]
Out=
-Graphics-

In:=
Plot[ Im[ f[t] ], {t,-10,10}]
Out=
-Graphics-

In:=
ParametricPlot[ {Re[ f[t] ], Im[ f[t] ]}, {t,-10,10}]
Out=
-Graphics-

I hope this helps.

--Ian

-----------------------------------------------------------
Ian Collier
Wolfram Research, Inc.
-----------------------------------------------------------
tel:(217) 398-0700   fax:(217) 398-0747    ianc at wolfram.com