what does this mean , how and for what is it used ?

Question

dareen 2024-3-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2097116-what-does-this-mean-how-and-for-what-is-it-used

编辑： dareen 2024-3-21

采纳的回答： Chunru

while playing around in the command window with arrays and matrices i tried to

print x=ones and it gave me an array of size 1*1 containing 1

x=ones(2,3) a matrix of size 2*3 containing ones ,

x=ones(2,3,4) builds the matrix of the size i wrote and repeats it 4 times

to here there are no problems i think,

x=ones(2,3,4,5,8)

this i am not sure what it excatly does and what for ,though its written in the documentations brifely that it should be an array of 2*3*4*5*8

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Sudarsanan A K 2024-3-21

Hi Dareen,

In MATLAB, the function "ones" is used to create arrays filled with the value 1. The syntax ones(d1, d2, d3, ..., dn) creates an n-dimensional array where d1, d2, d3, ..., dn specify the size of each dimension.

For your specific case:

x = ones(2,3,4,5,8) creates a 5-dimensional array where:

The first dimension has a size of 2.
The second dimension has a size of 3.
The third dimension has a size of 4.
The fourth dimension has a size of 5.
The fifth dimension has a size of 8.

This results in an array with a total of

elements, all of which are 1. Such high-dimensional arrays are useful in various advanced applications like data science, machine learning, signal processing, and scientific computing, where they can represent complex data sets or simulations with multiple variables or dimensions.

Manipulating and understanding these high-dimensional arrays require familiarity with MATLAB's array indexing and manipulation capabilities, enabling you to extract, analyze, and visualize the data contained within these structures effectively. Refer the documentation for further understanding:

https://www.mathworks.com/help/matlab/ref/ones.html

Hope this helps.

Stephen23 2024-3-21

编辑：Stephen23 2024-3-21

Example: the motion of a rigid body in 3D space fundamentally has six degrees of freedom. Each dimension is nominally independent of the other dimensions. So if you do some measurements for along each of those six dimensions, then you could store the measured data in a 6D array.

This is fundamentally no different to 2D data (e.g. an image) or any other number of dimensions of a system.

dareen 2024-3-21

编辑：dareen 2024-3-21

@Stephen23 thanks the example is really useful cleared this a lot, hopefully will impelement this in future codes

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Answer 1

Chunru 2024-3-21

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2097116-what-does-this-mean-how-and-for-what-is-it-used#answer_1428796

在 MATLAB Online 中打开

The following will produce a 5-dimensional array of 2x3x5x5x8. You can access the element by specifying 5-d index

x=ones(2,3,4,5,8)
x = 
x(:,:,1,1,1) =

     1     1     1
     1     1     1

x(:,:,2,1,1) =

     1     1     1
     1     1     1

x(:,:,3,1,1) =

     1     1     1
     1     1     1

x(:,:,4,1,1) =

     1     1     1
     1     1     1

x(:,:,1,2,1) =

     1     1     1
     1     1     1

x(:,:,2,2,1) =

     1     1     1
     1     1     1

x(:,:,3,2,1) =

     1     1     1
     1     1     1

x(:,:,4,2,1) =

     1     1     1
     1     1     1

x(:,:,1,3,1) =

     1     1     1
     1     1     1

x(:,:,2,3,1) =

     1     1     1
     1     1     1

x(:,:,3,3,1) =

     1     1     1
     1     1     1

x(:,:,4,3,1) =

     1     1     1
     1     1     1

x(:,:,1,4,1) =

     1     1     1
     1     1     1

x(:,:,2,4,1) =

     1     1     1
     1     1     1

x(:,:,3,4,1) =

     1     1     1
     1     1     1

x(:,:,4,4,1) =

     1     1     1
     1     1     1

x(:,:,1,5,1) =

     1     1     1
     1     1     1

x(:,:,2,5,1) =

     1     1     1
     1     1     1

x(:,:,3,5,1) =

     1     1     1
     1     1     1

x(:,:,4,5,1) =

     1     1     1
     1     1     1

x(:,:,1,1,2) =

     1     1     1
     1     1     1

x(:,:,2,1,2) =

     1     1     1
     1     1     1

x(:,:,3,1,2) =

     1     1     1
     1     1     1

x(:,:,4,1,2) =

     1     1     1
     1     1     1

x(:,:,1,2,2) =

     1     1     1
     1     1     1

x(:,:,2,2,2) =

     1     1     1
     1     1     1

x(:,:,3,2,2) =

     1     1     1
     1     1     1

x(:,:,4,2,2) =

     1     1     1
     1     1     1

x(:,:,1,3,2) =

     1     1     1
     1     1     1

x(:,:,2,3,2) =

     1     1     1
     1     1     1

x(:,:,3,3,2) =

     1     1     1
     1     1     1

x(:,:,4,3,2) =

     1     1     1
     1     1     1

x(:,:,1,4,2) =

     1     1     1
     1     1     1

x(:,:,2,4,2) =

     1     1     1
     1     1     1

x(:,:,3,4,2) =

     1     1     1
     1     1     1

x(:,:,4,4,2) =

     1     1     1
     1     1     1

x(:,:,1,5,2) =

     1     1     1
     1     1     1

x(:,:,2,5,2) =

     1     1     1
     1     1     1

x(:,:,3,5,2) =

     1     1     1
     1     1     1

x(:,:,4,5,2) =

     1     1     1
     1     1     1

x(:,:,1,1,3) =

     1     1     1
     1     1     1

x(:,:,2,1,3) =

     1     1     1
     1     1     1

x(:,:,3,1,3) =

     1     1     1
     1     1     1

x(:,:,4,1,3) =

     1     1     1
     1     1     1

x(:,:,1,2,3) =

     1     1     1
     1     1     1

x(:,:,2,2,3) =

     1     1     1
     1     1     1

x(:,:,3,2,3) =

     1     1     1
     1     1     1

x(:,:,4,2,3) =

     1     1     1
     1     1     1

x(:,:,1,3,3) =

     1     1     1
     1     1     1

x(:,:,2,3,3) =

     1     1     1
     1     1     1

x(:,:,3,3,3) =

     1     1     1
     1     1     1

x(:,:,4,3,3) =

     1     1     1
     1     1     1

x(:,:,1,4,3) =

     1     1     1
     1     1     1

x(:,:,2,4,3) =

     1     1     1
     1     1     1

x(:,:,3,4,3) =

     1     1     1
     1     1     1

x(:,:,4,4,3) =

     1     1     1
     1     1     1

x(:,:,1,5,3) =

     1     1     1
     1     1     1

x(:,:,2,5,3) =

     1     1     1
     1     1     1

x(:,:,3,5,3) =

     1     1     1
     1     1     1

x(:,:,4,5,3) =

     1     1     1
     1     1     1

x(:,:,1,1,4) =

     1     1     1
     1     1     1

x(:,:,2,1,4) =

     1     1     1
     1     1     1

x(:,:,3,1,4) =

     1     1     1
     1     1     1

x(:,:,4,1,4) =

     1     1     1
     1     1     1

x(:,:,1,2,4) =

     1     1     1
     1     1     1

x(:,:,2,2,4) =

     1     1     1
     1     1     1

x(:,:,3,2,4) =

     1     1     1
     1     1     1

x(:,:,4,2,4) =

     1     1     1
     1     1     1

x(:,:,1,3,4) =

     1     1     1
     1     1     1

x(:,:,2,3,4) =

     1     1     1
     1     1     1

x(:,:,3,3,4) =

     1     1     1
     1     1     1

x(:,:,4,3,4) =

     1     1     1
     1     1     1

x(:,:,1,4,4) =

     1     1     1
     1     1     1

x(:,:,2,4,4) =

     1     1     1
     1     1     1

x(:,:,3,4,4) =

     1     1     1
     1     1     1

x(:,:,4,4,4) =

     1     1     1
     1     1     1

x(:,:,1,5,4) =

     1     1     1
     1     1     1

x(:,:,2,5,4) =

     1     1     1
     1     1     1

x(:,:,3,5,4) =

     1     1     1
     1     1     1

x(:,:,4,5,4) =

     1     1     1
     1     1     1

x(:,:,1,1,5) =

     1     1     1
     1     1     1

x(:,:,2,1,5) =

     1     1     1
     1     1     1

x(:,:,3,1,5) =

     1     1     1
     1     1     1

x(:,:,4,1,5) =

     1     1     1
     1     1     1

x(:,:,1,2,5) =

     1     1     1
     1     1     1

x(:,:,2,2,5) =

     1     1     1
     1     1     1

x(:,:,3,2,5) =

     1     1     1
     1     1     1

x(:,:,4,2,5) =

     1     1     1
     1     1     1

x(:,:,1,3,5) =

     1     1     1
     1     1     1

x(:,:,2,3,5) =

     1     1     1
     1     1     1

x(:,:,3,3,5) =

     1     1     1
     1     1     1

x(:,:,4,3,5) =

     1     1     1
     1     1     1

x(:,:,1,4,5) =

     1     1     1
     1     1     1

x(:,:,2,4,5) =

     1     1     1
     1     1     1

x(:,:,3,4,5) =

     1     1     1
     1     1     1

x(:,:,4,4,5) =

     1     1     1
     1     1     1

x(:,:,1,5,5) =

     1     1     1
     1     1     1

x(:,:,2,5,5) =

     1     1     1
     1     1     1

x(:,:,3,5,5) =

     1     1     1
     1     1     1

x(:,:,4,5,5) =

     1     1     1
     1     1     1

x(:,:,1,1,6) =

     1     1     1
     1     1     1

x(:,:,2,1,6) =

     1     1     1
     1     1     1

x(:,:,3,1,6) =

     1     1     1
     1     1     1

x(:,:,4,1,6) =

     1     1     1
     1     1     1

x(:,:,1,2,6) =

     1     1     1
     1     1     1

x(:,:,2,2,6) =

     1     1     1
     1     1     1

x(:,:,3,2,6) =

     1     1     1
     1     1     1

x(:,:,4,2,6) =

     1     1     1
     1     1     1

x(:,:,1,3,6) =

     1     1     1
     1     1     1

x(:,:,2,3,6) =

     1     1     1
     1     1     1

x(:,:,3,3,6) =

     1     1     1
     1     1     1

x(:,:,4,3,6) =

     1     1     1
     1     1     1

x(:,:,1,4,6) =

     1     1     1
     1     1     1

x(:,:,2,4,6) =

     1     1     1
     1     1     1

x(:,:,3,4,6) =

     1     1     1
     1     1     1

x(:,:,4,4,6) =

     1     1     1
     1     1     1

x(:,:,1,5,6) =

     1     1     1
     1     1     1

x(:,:,2,5,6) =

     1     1     1
     1     1     1

x(:,:,3,5,6) =

     1     1     1
     1     1     1

x(:,:,4,5,6) =

     1     1     1
     1     1     1

x(:,:,1,1,7) =

     1     1     1
     1     1     1

x(:,:,2,1,7) =

     1     1     1
     1     1     1

x(:,:,3,1,7) =

     1     1     1
     1     1     1

x(:,:,4,1,7) =

     1     1     1
     1     1     1

x(:,:,1,2,7) =

     1     1     1
     1     1     1

x(:,:,2,2,7) =

     1     1     1
     1     1     1

x(:,:,3,2,7) =

     1     1     1
     1     1     1

x(:,:,4,2,7) =

     1     1     1
     1     1     1

x(:,:,1,3,7) =

     1     1     1
     1     1     1

x(:,:,2,3,7) =

     1     1     1
     1     1     1

x(:,:,3,3,7) =

     1     1     1
     1     1     1

x(:,:,4,3,7) =

     1     1     1
     1     1     1

x(:,:,1,4,7) =

     1     1     1
     1     1     1

x(:,:,2,4,7) =

     1     1     1
     1     1     1

x(:,:,3,4,7) =

     1     1     1
     1     1     1

x(:,:,4,4,7) =

     1     1     1
     1     1     1

x(:,:,1,5,7) =

     1     1     1
     1     1     1

x(:,:,2,5,7) =

     1     1     1
     1     1     1

x(:,:,3,5,7) =

     1     1     1
     1     1     1

x(:,:,4,5,7) =

     1     1     1
     1     1     1

x(:,:,1,1,8) =

     1     1     1
     1     1     1

x(:,:,2,1,8) =

     1     1     1
     1     1     1

x(:,:,3,1,8) =

     1     1     1
     1     1     1

x(:,:,4,1,8) =

     1     1     1
     1     1     1

x(:,:,1,2,8) =

     1     1     1
     1     1     1

x(:,:,2,2,8) =

     1     1     1
     1     1     1

x(:,:,3,2,8) =

     1     1     1
     1     1     1

x(:,:,4,2,8) =

     1     1     1
     1     1     1

x(:,:,1,3,8) =

     1     1     1
     1     1     1

x(:,:,2,3,8) =

     1     1     1
     1     1     1

x(:,:,3,3,8) =

     1     1     1
     1     1     1

x(:,:,4,3,8) =

     1     1     1
     1     1     1

x(:,:,1,4,8) =

     1     1     1
     1     1     1

x(:,:,2,4,8) =

     1     1     1
     1     1     1

x(:,:,3,4,8) =

     1     1     1
     1     1     1

x(:,:,4,4,8) =

     1     1     1
     1     1     1

x(:,:,1,5,8) =

     1     1     1
     1     1     1

x(:,:,2,5,8) =

     1     1     1
     1     1     1

x(:,:,3,5,8) =

     1     1     1
     1     1     1

x(:,:,4,5,8) =

     1     1     1
     1     1     1
y = x(2, 1, 3, 3, 4)   % one element of the 5-d array
y = 1

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Stephen23 2024-3-21

"i think my confusion is more related to not being familar with anything higher tha 2d arrays"

Mathematics is not limited to working in two dimensions, why would MATLAB be?

dareen 2024-3-21

makes sense this language is much more useful than i imagined

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