How to assign gaussian random numbers on meshgrid?

Question

Sudipta Sinha 2017-8-5

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编辑： Sudipta Sinha 2017-8-5

Hi,

I have very simple problem regarding assigning gaussian or uniform random numbers, and zeros on each of the meshgrid points. I tried with following way

nx=6;
ny=6;
[x,y]=meshgrid(1:nx,1:ny);
M=[x(:),y(:);zeros(nx,ny)]; 
M=[x(:),y(:);normrnd(nx,ny)];

However, it does not work. I am missing the correct syntax. Could anyone help me to rectify it?

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Answer 1

Star Strider 2017-8-5

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Try this:

nx=6;
ny=6;
[x,y]=meshgrid(1:nx,1:ny);
zg = randn(size(x));                            % Gaussian Random Numbers
zu = rand(size(x));                              % Uniform Random Numbers
figure(1)
surf(x,y,zg)
grid on
title('Gaussian Random Numbers')
figure(2)
surf(x,y,zu)
grid on
title('Uniform Random Numbers')

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Sudipta Sinha 2017-8-5

Thanks for your response. But my problem is different.I need to assign a random number or a constant number at each of the location of the meshgrid, M. For example

M(1,1)=rand1 M(1,2)=rand2 .... like that

I don't need to draw any figure with the data.

Star Strider 2017-8-5

The figures are simply to demonstrate the code.

The ‘zg’ and ‘zu’ arrays are the assignments you want.

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Answer 2

Walter Roberson 2017-8-5

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https://ww2.mathworks.cn/matlabcentral/answers/351627-how-to-assign-gaussian-random-numbers-on-meshgrid#answer_276890

在 MATLAB Online 中打开

You have

nx=6;
ny=6;
[x,y]=meshgrid(1:nx,1:ny);

After that, x and y are going to be 6 x 6.

Then you have

M=[x(:),y(:);zeros(nx,ny)];

The x(:) part is going to reshape the 6 x 6 x array into (6*6) x 1 . The y(:) is going to reshape the 6 x 6 y array into (6*6) x 1. The x(:),y(:) is therefore going to be 36 x 2

The zeros(nx,ny) is going to be 6 x 6.

Now, you are using ";" between those parts, so you are trying to put the 6 x 6 array "below" the 36 x 2 array.

If you need an array with x and y and z coordinates for some reason, then I would suggest

M=[x(:), y(:), zeros(nx*ny, 1)];

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Sudipta Sinha 2017-8-5

编辑：Sudipta Sinha 2017-8-5

No, it does not work. I need very simple thing. For each location of a grid point, I want to assign zero or random numbers. For example, if I wish to assign a value of a function (say, f=xy ) on each of the grid points, I need perform a very simple operation like f=x.*y. The dimension of the matrix, f, is defined by the dimension of x and y. However, how to pass the x and y information for generating correct dimension of zero and random numbers on each of the grid points.

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