How to generate a function from x-y vectors?

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Ajay Goyal
Ajay Goyal 2017-2-6
评论： Ghenam Dahmane 2022-3-4
Hello MATLAB users. I got two vectors (say x and y). Is there any way to create a function i.e. y=f(x). I do not want the expression. I just want to create the function in matlab for further calculations. For ease: x=[1 5 0 32 8]; y=[10 1 654 32 100];
  2 个评论
the cyclist
the cyclist 2017-2-6
Your question is not clear. What does "use these vectors in function form" mean?
Do you mean you want to find a function f(x) that will (approximately?) fit the x-y data? If so, what type of function? A polynomial?
Ajay Goyal
Ajay Goyal 2017-2-6
编辑：Ajay Goyal 2017-2-6
If I do not get expression; its ok. I just want to create a funtion from these vectors so that further calculations like Fourier series etc can be done

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采纳的回答

Nicolas Schmit
Nicolas Schmit 2017-9-4
You question is not very clear, so I will try to guess what you are trying to do.
If you want to define a purely symbolic function f(x), use the following syntax.
syms f(x)
If you want to create a function from data points x and y, use the griddedInterpolant function to create a interpolation of x and y.
x=[1 5 0 32 8];
y=[10 1 654 32 100];
[~, index] = sort(x);
F = griddedInterpolant(x(index), y(index));

更多回答（3 个）

Yifan Ma
Yifan Ma 2018-2-6
What you are looking for is map container. https://de.mathworks.com/help/matlab/ref/containers.map-class.html
Luca
Luca 2020-3-31
编辑：Luca 2020-3-31
Hi,
I have 2 vector (x, y) and I desire math expression y=f(x)
x must be syms. How to?
tnks
  2 个评论
Ajay Goyal
Ajay Goyal 2020-3-31
编辑：Ajay Goyal 2020-3-31
Hi,
As much I did understood your query, you wish to establish relation as y=f(x) and values of x are not known. To answer, I believe, it is not possible as the values of x and y is the first necessity to develop a function. Then only you may use it to predict y for input values of x.
Contrary, if you just want to define a function, you may do it following way:
%%%%Main File:
syms x
[ y ] = Untitled2( x )
%%%%Function file:
function [ y ] = Untitled2( x ) %%%%same name as in main file. Func. file will be stored with this name
y=x.^2; %%%%wrtite the function. Say
end
Kindly let me know, if your query has been resolved.
Best Luck
Ajay

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Luca
Luca 2020-3-31
编辑：Luca 2020-3-31
For you.

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