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MathGroup Archive 2005

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Re: Re: Re: Matrix Operator form using Mathematica

  • To: mathgroup at smc.vnet.net
  • Subject: [mg53229] Re: [mg53217] Re: [mg53216] Re: Matrix Operator form using Mathematica
  • From: "yehuda ben-shimol" <benshimo at bgumail.bgu.ac.il>
  • Date: Sat, 1 Jan 2005 02:33:49 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

First use map that will operate on the list, one item at a time (or make its
Attributes Listable).
That is,
aone2 = aone /@ {Tan[x], 1};
Second, since this is a matrix of operators, you get a matrix of results for
EACH item.
If you check the help on VectorQ
?VectorQ
You get 
VectorQ[expr] gives True if expr is a list or a one-dimensional SparseArray 
object, none of whose elements are themselves lists, and gives False 
otherwise. VectorQ[expr, test] gives True only if test yields True when 
applied to each of the elements in expr.
But Dimensions[one1] returns
{2,2}
and Dimensions[aone2] returns {2,2,2}
yehuda

-----Original Message-----
From: Pratik Desai [mailto:pdesai1 at umbc.edu] 
To: mathgroup at smc.vnet.net
Subject: [mg53229] [mg53217] Re: [mg53216] Re: Matrix Operator form using Mathematica

Thanks Steve for your response,

What if the matrix operates on a vector,
aone1=aone[{Tan[x],1}];
VectorQ[aone1]

Output:
False

Actually when the matrix aone operates on a 2*1 vector, it should give me 
another 2*1 vector,--I then want to multiply this new vector to another row 
vector to give me back a matrix. Is this possible

Thanks again,

Pratik





------ Original Message ----- 
From: "Steve Luttrell" <steve_usenet at _removemefirst_luttrell.org.uk>
To: mathgroup at smc.vnet.net
Subject: [mg53229] [mg53217] [mg53216] Re: Matrix Operator form using Mathematica


> Oops! I missed out a # from my first reply:
>
> One way to do this is to define a matrix-valued function
>
> aone={{-#,0},{0,D[#,{x,2}]}}&
>
> so that (for instance) evaluating
>
> aone[Tan[x]]
>
> gives the result
>
> {{-Tan[x], 0}, {0, 2*Sec[x]^2*Tan[x]}}
>
> Steve Luttrell
>
> "Pratik Desai" <pdesai1 at umbc.edu> wrote in message
> news:cqtc4e$7ic$1 at smc.vnet.net...
>>
>> Hello all,
>>
>> How do I define an operator embedded in a matrix and functions
>> as...well........an operator
>>
>> azero={{0,1},{1,0.05}};
>> aone={{-1,0},{0,(k)}};
>> (*k is the second order differential operator with respect to x d,xx, Is
>> there a way to define this in mathematica *)
>>
>>
>> Thanks
>>
>> Pratik Desai
>>
>
> 



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