MATLAB: How to use scatteredInterpolant

interpolationscatterdinterpolant

Dear all,

I am trying to make the plot below look better, and since I don't have enough data for that I would like to use the scatterdInterpolant command. However, what I am using so far does not work. Do you have any ideas?

I thank you in advance.

Cheers, Manolis

Best Answer

Have a look on imresize and/or interp2

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MATLAB: What’s the difference between interp3 and scatteredinterpolant

The figures in the MATLAB documentation should help you to understand the difference:

http://www.mathworks.com/help/matlab/math/overview-of-interpolation-techniques.html

In essence:

gridded data consist of data points at every node of an axis-aligned ND-grid. The functions ndgrid and meshgrid are often used to generate the (axis) indices for all of these points: you should look at their outputs.
scattered data consist of other data arrangements. Keep in mind that gridded data must include all data points on the grid: as soon as just one node is missing it becomes scattered data.

The choice is easy: do you have a data value for every node on some (N-D) grid?

 yes -> gridded data
 no  -> scattered data.

MATLAB: Any alternative function to speed up the interpolation process? because interp1 is very slow

The crystal ball is so foggy.

1. We have no idea how much data you have. Big problems take longer to solve. Sometimes you just need to accept that fact, and get some coffee while you wait.

2. We have no idea what method you are using in interp1. pchip will be faster than spline. Linear faster yet.

3. We have no idea how you are calling it. For example, are you calling with ONE point at a time, using a spline method, but on the same set of data? This will force interp1 to recompute the spline over and over again.

If 3 is the case, then create an interpolant using a tool like spline or pchip IN ADVANCE. Then use tools like ppval to evaluate the spline. This avoids recomputing the spline repeatedly.

If your data is changing constantly, and you need to use a smooth interpolant, then accept that it will take longer than you wish, or use a lower order interpolant which will be faster.

Best Answer

Related Solutions

MATLAB: What’s the difference between interp3 and scatteredinterpolant

MATLAB: Any alternative function to speed up the interpolation process? because interp1 is very slow

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