Defining a 4d double

Question

Anantha Padmanabhan 2017-6-13

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/344530-defining-a-4d-double

评论： Faqih Romi 2021-8-4

I am trying to build a 4D matrix from a velocity time series so that I can use it as an input to another program. My wind field is a M*N matrix where M is the number of points on the square grid and N is the measurement time in seconds (sampling at 1 hz). I now want to build a 4D array following which should look like this

4D_matrix=[time(1*N) velocity(M*N) x_coord(M,1) y_coord(M,1)];

How do i write this?

Thank you, Ananth

5 个评论
显示 3更早的评论隐藏 3更早的评论

Anantha Padmanabhan 2017-6-13

As said, M=676 (number of grid points) N=600 (for 10 minute simulations)

Faqih Romi 2021-8-4

d=[2 3 4 1; 3 2 1 4];

dd(:,:,:,1)=d(1,:,1);

dd(:,:,:,2)=d(2,:,1);

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Guillaume 2017-6-13

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/344530-defining-a-4d-double#answer_270538

Well, you need 676^3 * 600^2 * 8 bytes ~= 890 TB of memory to store that many elements, regardless of the shape. Chances are you don't have a computer with that much memory (not even in the ballpark).

You need to rethink what you want to do. In particular, I would think that x_coord and y_coord correspond to the rows and columns of your velocity field, therefore it does not make sense to store them in additional dimensions of the same matrix (as that would wastefully repeat the same values).

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

Pawel Tokarczuk 2017-6-13

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/344530-defining-a-4d-double#answer_270559

在 MATLAB Online 中打开

I think what you need is something like:

Velocity = zeros([NROWS, NCOLS, NTIMES], 'double');
[ X, Y ] = meshgrid(0:NCOLS-1, 0:NROWS-1);
XX = X0 + ScaleX*X;
YY = Y0 + ScaleY*Y;
T  = double(0:NTIMES-1);
TT = T0 + ScaleT*Time;