Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Notice: We are no longer accepting new posts, but the forums will continue to be readable.

Topic: declaring variables
Replies: 3   Last Post: Sep 16, 1996 10:33 PM

 Messages: [ Previous | Next ]
 Victoria Steblina Posts: 18 Registered: 12/7/04
Re: declaring variables
Posted: Sep 13, 1996 1:00 PM

>Dear math users,
>just a simple problem, but I got no answer from thew book.
>Re[x + I y] gives
>Re[x + I y]
>whereas
>Re[2 + 3 I]
>gives 2
>How could I tell Mathematica that x and y are real numbers?

There is a package <<Algebra`ReIm` that lets you specify that given
variables are purely real. Try the following:

In[5]:= Needs["Algebra`ReIm`"]

Im[x]^=0;

Im[y]^=0;

Re[x + I y]

Im[x + I y]

Out[8]= x
Out[9]= y

The up definitions make the assignment associated with x and y rather
than
with Im...

Hope this helps
Vicki

________________________________________________________________________

Victoria Steblina Email: vvs124@rsphy1.anu.edu.au
Optical Sciences Centre Tel: 61 6 249 5129
Australian National University Fax: 61 6 249 5184

Date Subject Author
9/5/96 Burkhardt Goedde
9/13/96 Victoria Steblina
9/13/96 Stephen P Luttrell
9/16/96 Daniel Lichtblau