### Highlights from Lagrange polynomial interpolation

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# Lagrange polynomial interpolation

### Carlo Castoldi (view profile)

07 Oct 2001 (Updated )

Lagrange polynomial interpolation

File Information
Description

Approx a point-defined function using Lagrange polinomial interpolation method

Acknowledgements
MATLAB release MATLAB 5.2 (R10)
09 Jul 2014 Marco Castelli

### Marco Castelli (view profile)

Very effective

16 Aug 2012 Xiangbin Guo

### Xiangbin Guo (view profile)

if you can explain in the behind of the code，it will be much better，thank you very much

28 Feb 2012 Tiffany

### Tiffany (view profile)

I do not understand why you need ",2" when you are determining the size of pointx. Why can't you just code n=size(pointx)? I am new to matlab, can someone explain?

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25 Oct 2011 Andrew

### Andrew (view profile)

To answer some of those questions here is an example of input:
x=linspace(-10,10,500);
lagrange(x,[x0,...,xn],[f(x0),...f(xn)])
where [x0,...,xn] is pseudo-code for representing the x values as an array and [f(x0),...,f(xn)]. Then try to plot that lagrange against the function you are interpolating and you should see the desired results.

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15 Jun 2011 BobAlpha

### BobAlpha (view profile)

15 Mar 2011 Juan Camilo Medina

### Juan Camilo Medina (view profile)

Simple yet functional code. Thanks

anyone can give me example how to use it?
i need it for my study...

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11 Apr 2010 naser Rashwan

### naser Rashwan (view profile)

how to represent x, i represent the x as [1 0] but it did not give the right answer

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08 Dec 2009 Angela

### Angela (view profile)

and what exactly do you have to give as input??

15 Oct 2008 pamonz wank
21 Aug 2008 sanjay zine
30 May 2008 Satya Sudhakar Yedlapalli

Can be made as a basic matlab function

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04 May 2008 mahesh nair
29 Feb 2008 LAY Nary

I don't know

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03 Nov 2007 Pier Francesco Maria Gatti

what is x? :D

25 Oct 2007 hira manzoor
14 Jun 2007 Arc .

Very usefull - I need it for convertion to java code.

03 Jun 2007 imran aslam
07 Oct 2006 John D'Errico

Lagrange interpolation is one of those interpolation methods that beginning textbooks include, along the way to showing you some useful methods. I imagine the textbook authors want to show you some of the history of interpolation. The fact is, high order Lagrange interpolation of this ilk was a only ever a good idea BACK IN the time of Lagrange. There has actually been progress in knowledge since then. (Surprise!) This is a terribly poor choice of interpolation method today.

In general, splines or other methods like them (PCHIP) will be less likely to introduce interpolation artifacts, oscillations, etc. Splines will be FAR less sensitive to tiny amounts of noise than will a high order Lagrange.

Even if I choose to disregard the method it implements,
the code itself is poorly implemented. It is triply looped - totally unvectorized. Expect it to be slow and if you have a large number of points, it will take more memory than need be.

If you need to use an interpolation tool, start with interp1, spline, or pchip, or look to the splines toolbox for more choices.

28 May 2006 Jose Garcia

i am a student of electronics engr and hav to do numerical diff using lagrange

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09 Nov 2005 Haroon Awais

good work, but it is better to use Matlab "interp1" function.

25 Oct 2005 Jev Jeg
05 Oct 2005 frederico schultz

24 Jun 2005 STEFANO IANNARILLI

THANK YOU VERY MUCH FOR IT.
I NEEDED FOR MY STUDYING

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31 May 2005 T B

Great job!!! Good work!

11 May 2005 JJ LS

Very Good

22 Apr 2005 bill cosby

Thank you for a great program

09 Mar 2005 im einnor

flawless program!

10 Feb 2005 Aleksey Rozsdobudko

what did u write?????? It can write even a child!!!!
dont use such words as "for","while" and anything like that in the matlab cos it's STUPPIDNESS!!!!!!

Man u r a king and matlab is your bitch!!

23 Nov 2003 sima asgari

math

24 Sep 2003 Sukant Gupta
30 Apr 2003 t t

beautiful,

20 Feb 2003 oziel alcocer
22 Jan 2003 keene rolph

The source code is very fantastic.it is good for research especially for mathematics purpose.

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15 Jan 2002 steve xia