Re: Extension of MatrixExp
- To: mathgroup@smc.vnet.net
- Subject: [mg11740] Re: Extension of MatrixExp
- From: Allan Hayes <hay@haystack.demon.co.uk>
- Date: Thu, 26 Mar 1998 03:09:07 -0500
- References: <6f1kaq$f69@smc.vnet.net>
Fred Lang wrote:
>
> Dear MathGroup users,
>
> MatrixExp is not able to give me a nice answer in the following very
> easy case:
>
> In[1] = m = {{2,0,0},{0,3,0},{0,0,4}} ; (* A diagonal matrix *)
Yes, I get
In[1]:=
MatrixExp[m]
Out[1]=
2 3
RootSum[-24 + 26 #1 - 9 #1 + #1 & ,
#1 #1 #1 2
12 E - 7 E #1 + E #1
{{---------------------------, 0, 0},
2
26 - 18 #1 + 3 #1
#1 #1 #1 2
8 E - 6 E #1 + E #1
{0, --------------------------, 0},
2
26 - 18 #1 + 3 #1
#1 #1 #1 2
6 E - 5 E #1 + E #1
{0, 0, --------------------------}} & ]
2
26 - 18 #1 + 3 #1
We can do the following - though I think that it should not be necessary
In[3]:=
ToRadicals[%]
Out[3]=
2 3 4
{{E , 0, 0}, {0, E , 0}, {0, 0, E }}
--
Allan Hayes
Training and Consulting
Leicester, UK
hay@haystack.demon.co.uk
http://www.haystack.demon.co.uk
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