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Interpolation of matrix with data that is of different dimensions

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The code below attempts to interpolate from a matrix (13x10) which contains velocities corresponding to some x points(1x10) and y points (13x1). I need to find the velocity for the same 10 x points but with different y points (10x1). I have tried the following to interpolate the matrix, however, I can't get a code that runs. Am I using the correct technique? If so why isn't this working? And if not then I am grateful for any assistance.
x_points = [3,6,9,12,15,18,21,24,27,30]; % X values for the function
y_points = [1,2,3,4,5,6,7,8,9,10,11,12,13]; % Y values for the function
Yq = [12.7,11.16,11.68,10.99,12.98,3.61,9.291,0.18,9.86,3.64] % The points for which I need the function value
Xq = x_points
F = interp2(x_points,y_points,V1,x_points,interpolate_me); % Output the matrix withe the data

Accepted Answer

Walter Roberson
Walter Roberson on 13 Mar 2021
Edited: Walter Roberson on 13 Mar 2021
V1 = sort(randi(9,13,10));
x_points = [3,6,9,12,15,18,21,24,27,30]; % X values for the function
y_points = [1,2,3,4,5,6,7,8,9,10,11,12,13]; % Y values for the function
Yq = [12.7,11.16,11.68,10.99,12.98,3.61,9.291,0.18,9.86,3.64] % The points for which I need the function value
Yq = 1×10
12.7000 11.1600 11.6800 10.9900 12.9800 3.6100 9.2910 0.1800 9.8600 3.6400
Xq = x_points
Xq = 1×10
3 6 9 12 15 18 21 24 27 30
F = interp2(x_points,y_points,V1, Xq, Yq); % Output the matrix withe the data
F
F = 1×10
8.7000 7.1600 9.0000 8.0000 8.9800 2.6100 5.5820 NaN 5.8600 3.0000
The Nan is because the Y query 0.18 is before any define y coordinate.
  2 Comments
James Rodriguez
James Rodriguez on 13 Mar 2021
Thank you so much! Works perfectly. If I wanted to run this for multiple functions (v1.v2...) , is there an efficent way of doing this? I tried to form one matrix with all the function matrices and run that but it will not give an ouput .
Walter Roberson
Walter Roberson on 13 Mar 2021
Not really. There is a temptation to say "use interp3" with the third coordinate being the function number, but the problem with that is that it will mix between functions. Though maybe if you used a third coordinate that was on a much larger scale then the mixing would be minimal.

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