Drexel dragonThe Math ForumDonate to the Math Forum


Math Forum
 Ask Dr. Math
 Discussions
 Internet Newsletter
 MathTools
 Problems of the Week
 Teacher2Teacher
 Teacher Exchange
 Workshops

Search All of the Math Forum:
Browse our Internet Mathematics Library

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


Math Forum » Discussions » Software » comp.soft-sys.matlab

Topic: complex results using ODE45
Replies: 3   Last Post: Oct 22, 2013 2:25 PM

Advanced Search
Reply to this Topic Reply to this Topic

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Nasser Abbasi

Posts: 5,730
Registered: 2/7/05
Re: complex results using ODE45
Posted: Oct 15, 2013 2:14 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On 10/15/2013 12:53 PM, Jeffrey wrote:
> I have the two m files given below. "a" and "T" are returned as complex with
>
> Why are values becoming complex?
>
> Please help.
>
> Jeff
> _______________________________
> %this is in file alpha.m
> function dadT = alpha(T,a)
> b = 20
> l= 50.1
> k=exp(l)
> ner = -36108.73
> n=1.269
> dadT = (k/b)*(exp(ner/T)) *((1-a)^n
> ________________________________________
>

You have missing ")" above btw. Last line.

But besides this, which I assume a cut/paste issue only,
look at the expression itself.

What happens for (1-a)^n, and "a" happens to be
larger than one?

EDU>> (1-1.5)^(1.269)

ans =

-0.2754 - 0.3104i

Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2015. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.