R help - May 2010 - Symbolic eigenvalues and eigenvectors

Let's say I had a matrix like this:

library(Ryacas)
x<-Sym("x")
m<-matrix(c(cos (x), sin(x), -sin(x), cos(x)), ncol=2)

How can I use R to obtain the eigenvalues and eigenvectors?

Thanks,
John

	[[alternative HTML version deleted]]

Hi,

On Tue, May 4, 2010 at 8:54 PM, John Mesheimer <john.mesheimer at
gmail.com> wrote:
> Let's say I had a matrix like this:
>
> library(Ryacas)
> x<-Sym("x")
> m<-matrix(c(cos (x), sin(x), -sin(x), cos(x)), ncol=2)
>
> How can I use R to obtain the eigenvalues and eigenvectors?
R> help.search('eigenvalues')

is a good start

-- 
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact

Eigenvalues are not directly supported by the Ryacas interface but you
can send this directly to yacas like this:
> yacas("EigenValues({{Cos(x), -Sin(x)}, {Sin(x), Cos(x)}})")
[1] "Starting Yacas!"
expression(Roots((cos(x) - xx)^2 + sin(x)^2))


On Tue, May 4, 2010 at 8:54 PM, John Mesheimer <john.mesheimer at
gmail.com> wrote:
> Let's say I had a matrix like this:
>
> library(Ryacas)
> x<-Sym("x")
> m<-matrix(c(cos (x), sin(x), -sin(x), cos(x)), ncol=2)
>
> How can I use R to obtain the eigenvalues and eigenvectors?
>
> Thanks,
> John
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

Hi John,

It's common courtesy to keep all discussions originating from R-help
back on list so it can act as a helpful resource for others to peruse
when they have similar questions.

With that in mind, I think you forgot to CC the list with your very
informative follow-up reply to me:

On Tue, May 4, 2010 at 9:22 PM, John Mesheimer <john.mesheimer at
gmail.com> wrote:
> Well, that reply was meant for the list.
>
> As for a personal reply.. well, you's pretty much a dumbass.
In this case, I thought it'd be helpful to let everyone here know how
nice you are when someone tries to help you out.

I was on my way out the door from school when I tried to shoot off a
quick email to help you find the answer to a problem that I
unfortunately misunderstood in your original email. I apologize for
not taking the time to appreciate the full details of your problem.

As for you, I guess you can apologize for, well, being you.

Good luck in your endeavors,

-steve
> On Tue, May 4, 2010 at 9:21 PM, John Mesheimer <john.mesheimer at
gmail.com>
> wrote:
>>
>> Really? Is it? Hadn't thought of that.
>>
>> Anybody else?
>>
>>
>> On Tue, May 4, 2010 at 9:06 PM, Steve Lianoglou
>> <mailinglist.honeypot at gmail.com> wrote:
>>>
>>> Hi,
>>>
>>> On Tue, May 4, 2010 at 8:54 PM, John Mesheimer <john.mesheimer
at gmail.com>
>>> wrote:
>>> > Let's say I had a matrix like this:
>>> >
>>> > library(Ryacas)
>>> > x<-Sym("x")
>>> > m<-matrix(c(cos (x), sin(x), -sin(x), cos(x)), ncol=2)
>>> >
>>> > How can I use R to obtain the eigenvalues and eigenvectors?
>>>
>>> R> help.search('eigenvalues')
>>>
>>> is a good start
>>>
>>> --
>>> Steve Lianoglou
>>> Graduate Student: Computational Systems Biology
>>> ?| Memorial Sloan-Kettering Cancer Center
>>> ?| Weill Medical College of Cornell University
>>> Contact Info: http://cbio.mskcc.org/~lianos/contact
>>
>
>


-- 
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact