How to Perform 3D Interpolation in MATLAB?

[FutureScience]

Hello everybody!

I'm dealing with a MATLAB script that is made up in this way:

I've this external loop

% ALTITUDE [ft]
h_ft = 0:200:10000;

% TEMPERATURE [°C]
T_C = 0:1:50;

for mm = 1:length(h)
    for nn = 1:length(T_0)

The aim of this loop is to calcuate a velocity, so at the end I obtain a V_0 of dimension 51x51.

I want to use this V_0 velocity to enter in a matrix where I've other altitude and temperature intervals, which are h_new = 0:1000:10000 and T_new = 0:5:50, and for a velocity vector V_T = 0:13.26:106.08 [m/s], I have the thrust values that you see in this picture:
http://img249.imageshack.us/img249/2285/image1ii.jpg
(Imagine a similar matrix for the other altitude values)

So for any iteration of the external loop, I want to enter with the previously calculated V_0 in the V_T range, and for each value of h_ft and T_0, which have different sizes compared with h_new and T_new, I want the corresponding thrust values for my V_0.

In the end I want to obtain a 51x51 thrust matrix, by interpolating h_new and T_new values, to find the ones for h_ft and T_0.

I've struggled with both interp2 and griddata, without much success, so I'm asking for your help!

Thanks in advance!

 

[mmwave]

Hello there,

Thank you for sharing your question with us. It seems like you are trying to interpolate values for thrust based on altitude and temperature using a given velocity. This can be achieved using the interp2 function in MATLAB.

First, you will need to organize your data into a grid format, with altitude as the rows and temperature as the columns. Then, you can use the interp2 function to interpolate the thrust values for the given velocity. Here's an example code:

% Define the grid for altitude and temperature
h_new = 0:1000:10000;
T_new = 0:5:50;

% Define the thrust values matrix for the given grid
thrust = [0 20 40 60 80 100 120 140 160 180;
10 30 50 70 90 110 130 150 170 190;
20 40 60 80 100 120 140 160 180 200;
30 50 70 90 110 130 150 170 190 210;
40 60 80 100 120 140 160 180 200 220;
50 70 90 110 130 150 170 190 210 230;
60 80 100 120 140 160 180 200 220 240;
70 90 110 130 150 170 190 210 230 250;
80 100 120 140 160 180 200 220 240 260;
90 110 130 150 170 190 210 230 250 270;
100 120 140 160 180 200 220 240 260 280];

% Define the velocity for which you want to interpolate
V_0 = 30;

% Use interp2 to interpolate the thrust values for the given velocity
thrust_interpolated = interp2(h_new, T_new, thrust, V_0);

% Display the interpolated thrust values
disp(thrust_interpolated);

You can use this code within your external loop to obtain a 51x51 thrust matrix. I hope this helps. Let me know if you have any further questions.