How can I increase the the number of data-points in a scattered data set?

I have a 461 by 3 matrix in which the first column is x coordinates, second one y and third one z coordinates. The values of the elements of z column is o. (i.e it is actually 2D data but I need 3D data for further calculation so I kept the third column.). The values of the data set are scattered values.

Now I want to get more coordinate values (x,y,z) within this data set. The z values will be zero.

Can I use the function interp1/2/3??? how??

My main problem is achieving the coordinate matrix with all (prev.+interpolated) values. The interp function shows the value of a desired point, but I do not need that.

Thanks in advance.

Answer 1

[David Sanchez]

M=rand(50,3);
M(:,3) = 0;
M = sort(M,1,'ascend');
% double the data in X column
x_extended = interp(M(:,1),2);
% dobule the data in Y column
y_extended = interp(M(:,2),2);
% new data containing all data
M_new = [x_extended,  y_extended, zeros(100,1)];

Answer 2

[Kheya Banerjee]

David, thank you very much. It woks perfectly! (as far as the data set is long enough)

Answer 3

[Kheya Banerjee]

David, there is a small problem. as I am considering the data as coordinates, (x,y), the actual data points become changed when you sorted it, isn't it right??

is there any way to keep the data combinations same???? i.e. x point and y point of a particular row (of the given data sheet) remains in the same row after interpolating,too.

Can you help me in this matter?

Answer 4

[David Sanchez]

Just skip the sort command, I did it for testing purposes. The interp will create new point in between every consecutive pair of data:

M = my_50x3_data_matrix;
x_extended = interp(M(:,1),2);
% dobule the data in Y column
y_extended = interp(M(:,2),2);
% new data containing all data
M_new = [x_extended,  y_extended, zeros(100,1)];

[Shins K]

When I used the same code, I am getting the error message "Unrecognized function or variable 'interp'". Could you please let me know why it is so, if you know?