How to create a 2D lookUp table in matlab

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Nadia A 2016-8-2

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评论： Walter Roberson 2017-9-8

I want to create a 2D look Up table from 3 arrays

x1= 0:0.1:1 %axis values --> length is 11
x2= 25:2:35 %axis values --> length is 6
y=  0.01:0.001:0.06 % output data --> length is 51, rest of the 15 elements are zeros

I want to create an LUT which has 6 rows and 11 columns. Whenever I need to retrieve y, if exact query points of x1 and x2 is not present, then the function should give an interpolated value. I want to generate a .m script for this without using Simulink.

Anyone please help me with this.

Thanks

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Walter Roberson 2016-8-2

length(y) is 51. If you were given the J'th x1 value exactly and the K'th x2 value exactly (so no interpolation needed), which of the 51 y values should be output?

Nadia A 2016-8-2

编辑：Nadia A 2016-8-2

Sorry, rest of the values is assigned as 0.I have edited my original post.

Thanks

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Answer 1

Stephen23 2016-8-2

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You could use interp2 or interpn:

>> x1 = 0:0.1:1;
>> x2 = 25:2:35;
>> y = 0.01:0.001:0.06;
>> vm = zeros(numel(x1),numel(x2));
>> vm(1:numel(y)) = y;
>> interpn(x1,x2,vm,0,25)
ans =  0.010000

Note that this allocates the values of y row-wise into mat. If you want them to be allocated column-wise then transpose mat before and after the allocation.

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Walter Roberson 2017-9-8

You need a scattered interpolant for that case. You should expect that off-diagonal might look fairly different than you imagine, as interpolation will come to depend upon which triangle happens to be closest in 3 space.

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