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 >> > >