MaplePrimes - Questions and Posts tagged with linearalgebra

Search in a Matrix

hsadeghi — Mon, 14 May 2012 22:05:43 Z

I'm using Linearalgebra and suppose I have a 10x10 matrix. I want to find the closest element in each column of the matrix to 100. Any idea how to do it?

A question about the memory requirement of generalized eigenvalue solver in Maple 10 and further versions

smith_alpha — Fri, 27 Apr 2012 11:50:03 Z

Dear everyone,

I have a question about the memory requirement of generalized eigenvalue solver in Maple 10 and further versions.

Suppose I have a code like

***

with(LinearAlgebra):
Digits:=34;
n:=30;
A:=Matrix(n,n);
B:=Matrix(n,n);

for i from 1 to n do
for j from 1 to n do
     if i=j then
       A[i,j]:=i*j;
       B[i,j]:=1;...

Kernel connection lost on very simple LinearAlgebra

fredbel6 — Mon, 16 Apr 2012 14:02:43 Z

Hello

I am using Maple 15 on a Macbook Pro, and I was using this simple code

restart;with(LinearAlgebra):
P := Matrix(4, 4, [[1, s, t, 0], [0, 1, s, 0], [0, 0, 1, s], [0, 0, 0, s]]);
DiagonalMatrix(Column(P, 2)).P;

which should be easy but then Maple gives me a pop-up message:

"Kernel connection has been lost. The kernel returned the following error message:

How to write the equation of the line?

toandhsp — Thu, 05 Apr 2012 06:12:42 Z

I want to write the equation of the line which passing the two point A(1, 1) and B(m+1, -2*m + 2) by using LinearAlgebra, but i can not write. Please help me. Thank you.

D can be unprotected, but is still seen as operator?

fredbel6 — Thu, 15 Mar 2012 07:14:35 Z

Hello,

I always used something different from D when using diagonal matrices. Now I learned I can unprotect D.

However, I got this:

> restart; with(LinearAlgebra);
> unprotect(D);
> D := DiagonalMatrix([2, 3]);
> D.D;D^(2);
Error, invalid 'D' operator

Maple does interpret D as a matrix that he can square, but the exponentional notation can't be used as he sees it as some sort of operator? Can anyone point out my mistake?

Coordinates of a point (8)

toandhsp — Thu, 08 Mar 2012 15:32:36 Z

Problem. Let MNPQ be a square. Find the other two vertices, knowing that, the vertices M(5; 3; -1), P(2; 3; -4) and N lies on the plane x + y - z - 6 = 0.

This is my code

> restart:

with(LinearAlgebra):

M:=<5,3,-1>:

P:=<2,3,-4>:

N:=<x,y,z>:

A:=DotProduct(M-N,P-N,conjugate =false):

Can we optimize Matrix-Vector operations with the LinearAlgebra package or is O(n^3) ~ O(n^2)

viraghj — Mon, 27 Feb 2012 18:31:01 Z

The following example shows some typical computations with Householder- or reflextion matrices. Why are the second and third variants only slightly better than the first one? Could we get a real speedup without rtable/NAG/BLAS/etc. tricks?

$ maple15
|\^/| Maple 15 (X86 64 LINUX)
._|\| |/|_. Copyright (c) Maplesoft, a division of Waterloo Maple Inc. 2011
\ MAPLE / All...

dsolve,numeric: "Error, (in dsolve/numeric/BVPSolve) matrix is singular". Why?

Lars282 — Tue, 31 Jan 2012 11:20:33 Z

Hey everyone.

I have been trying to solve an ODE with BC with dsolve,numeric but always get the error below:

> Error, (in dsolve/numeric/BVPSolve) matrix is singular

My problem is not solving it (ie fine to do with LinearAlgebra package or similar), but why does this error occur? What is the problem with the ODE/BC that produces this error?

And is there a way of adjusting the ODE/BC to be able to solve it simply by using dsolve,numeric?

Joint Meetings Linear Algebra Example Generator

JeffKnisley — Thu, 05 Jan 2012 08:28:45 Z

One of the challenges in Linear Algebra is in developing problems, projects, and exercises that are both larger dimensional and student-accessible. Indeed, round-off error, computational complexity, difficulty factoring characteristic polynomials of degree 3 or higher, and similar aspects often mean that any problems or applications of rank 3 or higher are approached solely via technology.

However, that same technology can be used to create...

There is a bug in Vector[row] when n>10

alex_01 — Fri, 16 Dec 2011 14:56:13 Z

I have come across this previously but I never had the energy to report it.
The problem is that there exist a bug in Vector[row] when n>10.

For example run the below code:

restart:
with(LinearAlgebra):
a1 := Vector[row]([seq(w[i], i = 1 .. 5)]);
a2 := Vector[column]([seq(w[i], i = 1 .. 5)]);

a3 := Vector[row]([seq(w[i], i = 1 .. 20)]);
a4 := Vector[column]([seq(w[i], i = 1 .. 20)]);

a1.a2;
a3.a4;

...

LinearAlgebra[Generic][SmithForm] examples sought

eclark — Sat, 03 Sep 2011 07:03:09 Z

Does anyone happen to have a worksheet that implements LinearAlgebra[Generic][SmithForm]

for Euclidean domains like Z[w], w^3 = 1, or Z[sqrt(d)] where d = −11, −7, −3, −2, −1, 2, 3, 5, 6, 7, 11, 13, 17, 19, 21, 29, 33, 37, 41, 57, 73?

If so I would greatly appreciate receiving a copy of it.

--Edwin Clark

construct matrix of singular values

jalexanal — Sun, 28 Aug 2011 03:19:19 Z

I am using the LinearAlgebra package. The function SinbularValues returns the singular value matrix S as a vector, i.e.,S*<1,1,1..1>. Is there an easy way to recover S, itself, from this vector?

how to tell Maple that matrix is symmetric with real entries

rwether — Thu, 30 Jun 2011 22:02:17 Z

I was going to demonstrate the action of Maple for a symmetric 3 by 3 real matrix with 1, 2, and 3 distinct eigenvalues and got strange results. It may be that I need to explicitly tell Maple that the matrix is symmetric and real. (How would I do this?)

For example, after with(LinearAlgebra) I put tmat1:=Matrix(3,3,[1,2,3,2,4,5,3,5,6]), and get eigenvalues with small imaginary parts (!). When I put tmat2:=Matrix(3,3,[0,1,1,1,0,1,1,1,0...

Minimal polynomials in GF

Alec Mihailovs — Sun, 12 Jun 2011 15:42:17 Z

Answering to that question, I posted several procedures finding minimal polynomials for the elements of finite fields. The best one was the following,

alias(a=RootOf(T^100+T^97+T^96+T^93+T^91+T^89+T^87+T^86+T^82+T^81+T^71+T^70+T^67+T^61+
T^60+T^57+T^54+T^53+T^52+T^49+T^48+T^45+T^44+T^42+T^39+T^36+T^33+T^32+T^31+T^29+T^28+T^27+
T^26+T^24+T^23+T^22+T^18+T^17+T^16+T^14+T^13+T^12+T^10+T^8+T^7+T^6+T^3+T+1)):

F:=GF(2,100,op(a)):
z:=F:-input(2):

MinPolyGF:=proc(x,y:=_X)
local A, i;
A:=Matrix(100,...

Order of eigenvalues in LinearAlgebra:-Eigenvectors

PatrickT — Thu, 12 May 2011 18:53:31 Z

I am computing eigenvalues of a 3X3 square Matrix that contains symbolic elements and many zeros. There are 2 zero eigenvalues and 1 non-zero. I'd like to request Maple to order the eigenvalues in a certain way, with the non-zero eigenvalue first. Oddly, the command LinearAlgebra:-Eigenvectors(A); orders them in a seemingly random way, with the non-zero eigenvalue either first or last, never in the middle. The LinearAlgebra:-Eigenvalues(A); commands seems...