Making a NxN matrix.

2011 6 12
2 个回答
更新时间：2016 8 3
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http://www.math.ufl.edu/~liqing/Courses/MAS3114/project_3.pdf
I have a homework assignment and i'm trying to figure out some functions that could help me write the matrix in this form (on that link i posted) like if i wanted to make a row with 1000 ones and not have to write 1 a thousand times.. In my class they don't teach us the software so yeah, any help will be appreciated, thank you.

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回答（2 个）

Paulo Silva
Paulo Silva 2011-6-12

1 个投票

We don't make homeworks, we only help with answers to specific questions and if we are kind enough we might give some tips:
doc ones %execute this to see the documentation of the function ones
doc zeros %execute this to see the documentation of the function zeros
Simple example:
m=zeros(10,10); %create one array with 10 rows and columns full of zeros
m(5,:)=1; %all columns (:) from row number 5 are now equal to 1
m %see the array
Image Analyst
Image Analyst 2011-6-12

0 个投票

Like I said in my response to your post of this in the newsgroup:
Alan: To set an entire row to a value:
M(rowNumberToSet, :) = theValue;
Example:
M(42, :) = 2.718281828;
To set an entire column so a value:
M(:, columnNumberToSet) = theValue;
Example:
M(:, 69) = 3.14159;
This is basic MATLAB stuff - the stuff you learn the first couple of hours into it. You should find it early on in the "Getting Started" section of the help.

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Alan`
Alan` 2011-6-13
if i want a pattern like this one:
{1 1 1 1}
{1 2 2 2}
{1 2 3 3}
{1 2 3 4}
where pretty much what this is is a nxn where n is 4. what i noticed was
A(1,:)=1
A(:,1)=1
A(2,2:)=2
A(3,3:)=3
A(4,4:)=4
does this mean: A(n, n:)=n ???
im trying to develop a while loop to get this pattern.. i know C programming i'm currently in that class as well but as i said before we dont get Matlab trayning in Linear Algebra so im not familiar with all the commands.. how do i make a for loop or while loop on a case like this one.. i know how to do it for other operations, just not in a matrix form. I'd appreciate some intuition in this.
Alan`
Alan` 2011-6-13
training***
Andrei Bobrov
Andrei Bobrov 2011-6-13
Creates your matrix with loop.
% 1.
n = 4;
for j = n:-1:1, A(j,j:n)=j; A(j:n,j)=j; end
% 2
A=ones(n);
for j = 1:n, A(j:n,j:n)=j; end
Andrei Bobrov
Andrei Bobrov 2011-6-13
Hi Alan! Creates your matrix without loops.
% 1
A = repmat(1:4,4,1);
A = min(A,A.');
% 2
A = repmat(1:4,4,1);
A = tril(A) + triu(A.',1)
Walter Roberson
Walter Roberson 2016-8-3
Yaser Rostami comments to Andrei Bobrov
clear all; close all; clc m=zeros(5,7); g=0; c=numel(m); for d=1:c; g=1+g; m(d)=g; end

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