How to build a ''growing" matrix

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Sebastian Ciuban 2014-4-13

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https://ww2.mathworks.cn/matlabcentral/answers/125596-how-to-build-a-growing-matrix

评论： Image Analyst 2014-4-13

采纳的回答： Image Analyst

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In my example I have:

variable "i" (size 1x1) and R (size 3x3)

R = 1     0      0
    0   cos(i) sin(i)
    0  -cos(i) cos(i)

Now, how should I build "R" if my variable "i" has size 1 x n?

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Azzi Abdelmalek 2014-4-13

What is the size of R?

Sebastian Ciuban 2014-4-13

在 MATLAB Online 中打开

Well in the simple case lets say:

i=1
R=1     0      0
  0   cos(i) sin(i)
  0  -cos(i) cos(i)

But what if i=[1 3 5 5]. How I can make R to be computed for all the values of i?

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Answer 1

Image Analyst 2014-4-13

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cos(i) will be an array if i is an array. So that means that the elements of R must be cells since all elements of R are not the same size. The firs row and column of R are 1x1 while the lower right elements are 1 x 4. I really think you should avoid this route, but if you insist, start your study of cells here in the FAQ: http://matlab.wikia.com/wiki/FAQ#What_is_a_cell_array.3F. You'd probably be better off making R a 3D array though, with each plane of R being computed for a different value of i. Let us know which approach you want to take. If you don't know , then let us know what you plan on doing with R once you have it.