MATLAB: Creating a N-Dimentional matrix from a 2 Dimentional matrix

n-dimentional

Let's assume I have a as [1 2;3 4]. I need to create b to be 2-by-2-by-100 as follows: b(:,:,1)=[1 2;3 4] . . b(:,:,100)=[1 2;3 4]

I know that function 'cat' works but it's required to repeat the [1 2;3 4] hundred times which is not applicable. Which function should I use here?

Thanks,

Best Answer

a = [1 2 ;3 4]
b = reshape(repmat(a(:),1,100),[size(a) 100]);

Related Solutions

MATLAB: How to resize a matrix with zeros in between elements

Some general solutions for matrix A of any size.

>> A = [10,5;4,10;2,3];

Method one: sub2ind:

>> [R,C] = size(A);
>> B = zeros(C,R*C);
>> B(sub2ind(size(B),1+mod(0:R*C-1,C),1:R*C)) = A.'
B =
   10    0    4    0    2    0
    0    5    0   10    0    3

Method two: reshape:

>> [R,C] = size(A);
>> B = reshape([reshape(A.',1,[]);zeros(C,C*R)],[],R);
>> B = reshape(B(1:end-C,:),C,[])
B =
   10    0    4    0    2    0
    0    5    0   10    0    3

Method three: linear indexing:

>> [R,C] = size(A);
>> B = zeros((1+C)*C,R);
>> B(1:C+1:end-C) = A.';
>> B = reshape(B(1:end-C,:),C,[])
B =
   10    0    4    0    2    0
    0    5    0   10    0    3

Method four: blkdiag:

>> B = cell2mat(cellfun(@(c)blkdiag(c{:}),num2cell(num2cell(A),2),'uni',0).')
B =
   10    0    4    0    2    0
    0    5    0   10    0    3

MATLAB: How to calculate distance between a point and a line in 4D (or space higer than 3D)

No, there's not, but you can calculate it using the dot product and the norm for any number of dimensions:

numDim = 4;
A = rand(numDim,1); %Point in line

B = rand(numDim,1); %Point in line
P = rand(numDim,1); %Point outside line
pa = P - A;
ba = B - A;
t = dot(pa, ba)/dot(ba, ba);
your_dist = norm(pa - t * ba,2)

Best Answer

Related Solutions

MATLAB: How to resize a matrix with zeros in between elements

MATLAB: How to calculate distance between a point and a line in 4D (or space higer than 3D)

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