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From: Magdalena Moczydlowska on 24 Mar 2010 05:34
Hi,

Do you know how to estimate z (-1/2 exp(2*z)+3/2*exp(z)) where z is a
complex number ( Re(z)<0).

Thank You,
Magdalena

From: Tomas Garza on 25 Mar 2010 05:23
If by "estimate" you mean "evaluate", then just use the right syntax. The exponential function in Mathematica is written Exp, and its argument must be inside brackets "[" and "]". For example, if you wish to use z== -1 + I (a complex number with Re(z)<0, where I is the syntax for the imaginary i):

In[27]:== z (-1/2 Exp[2*z]+3/2*Exp[z])/.z->-1.+I

Out[27]== -0.729119-0.076501 I

I just copied your expression and substituted the exp() by Exp[]. The period after the last 1 is meant to give you a numerical value.

Tomas

> Date: Wed, 24 Mar 2010 04:43:19 -0500
> From: magdamoczydlowska(a)gmail.com
> Subject: estimation
> To: mathgroup(a)smc.vnet.net
>
> Hi,
>
> Do you know how to estimate z (-1/2 exp(2*z)+3/2*exp(z)) where z is a
> complex number ( Re(z)<0).
>
> Thank You,
> Magdalena
>
From: DrMajorBob on 25 Mar 2010 05:24
Estimate? Why not just compute it?

f[z_] = z (-1/2 Exp[2*z] + 3/2*Exp@z)

((3 E^z)/2 - E^(2 z)/2) z

f[RandomReal[{-10, 0}] + RandomReal[{-1, 1}]]

-0.244266

Bobby

On Wed, 24 Mar 2010 04:43:19 -0500, Magdalena Moczydlowska
<magdamoczydlowska(a)gmail.com> wrote:

> Hi,
>
> Do you know how to estimate z (-1/2 exp(2*z)+3/2*exp(z)) where z is a
> complex number ( Re(z)<0).
>
> Thank You,
> Magdalena
>


--
DrMajorBob(a)yahoo.com

From: Murray Eisenberg on 25 Mar 2010 05:26
Certainly the following does it:

z (-1/2 Exp[2 z] + 3/2 Exp[z])

But I suspect that's not really your question. Let me guess that you
really have z = x + I y and you want to evaluate the expression in a way
that collects the real and imaginary parts. In that case:

ComplexExpand[z (-1/2 Exp[2 z] + 3/2 Exp[z]) /. z -> x + I y]

On 3/24/2010 5:43 AM, Magdalena Moczydlowska wrote:
> Hi,
>
> Do you know how to estimate z (-1/2 exp(2*z)+3/2*exp(z)) where z is a
> complex number ( Re(z)<0).
>
> Thank You,
> Magdalena
>

--
Murray Eisenberg murray(a)math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower phone 413 549-1020 (H)
University of Massachusetts 413 545-2859 (W)
710 North Pleasant Street fax 413 545-1801
Amherst, MA 01003-9305

From: dh on 25 Mar 2010 05:22
Hi magdalena,
what do you mean by "estimation".
Daniel

On 24.03.2010 10:34, Magdalena Moczydlowska wrote:
> Hi,
>
> Do you know how to estimate z (-1/2 exp(2*z)+3/2*exp(z)) where z is a
> complex number ( Re(z)<0).
>
> Thank You,
> Magdalena
>



--

Daniel Huber
Metrohm Ltd.
Oberdorfstr. 68
CH-9100 Herisau
Tel. +41 71 353 8585, Fax +41 71 353 8907
E-Mail:<mailto:dh(a)metrohm.com>
Internet:<http://www.metrohm.com>


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