Obtaining (X, Y) coordinates of new points by interpolation for 5 known points

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I have 5 data points (experimental). I want to carry out cubic spline interpolation and extract (x,y) co-ordinates of '100' points between x=0 to 50. Can someone please help me with this problem.I am a beginner so i don't have much idea about it. I need a program in either matlab or python. Points are given below. someone please help me.

Points are (0,0.256) (12.5, 0.218) (25, 0.165) (37.5, 0.247) (50, 0.294).

Posted 5-Oct-15 17:42pm

Member 12035385

Updated 15-Nov-15 21:06pm

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dan!sh 6-Oct-15 0:49am

Do you know the polynomial that is used to generate the curve? You just need to solve the polynomial then to get N solutions.

Sergey Alexandrovich Kryukov 6-Oct-15 1:10am

To say so, you would need to know which interpolation method should be used, exactly. (And what are "N solutions"? N points is one solution, not N... and so on...) But probably you have a correct basic idea. Please see Solution 1.
—SA

dan!sh 6-Oct-15 1:15am

My point exactly. OP needs to know the polynomial. He must, since he will be generating the curve. So reading from screen representation of data is out of picture.

Sergey Alexandrovich Kryukov 6-Oct-15 1:22am

Yes, of course, I just say that polynomial interpolation is not the only kind of interpolation. The key is not trying to read from screen.
—SA

Member 12035385 6-Oct-15 1:23am

i am restricting to cubic spline

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Sergey Alexandrovich Kryukov · Accepted Answer · 2015-10-05T19:05:00

Solution 1

This is wrong approach.

Right approach would be this:

Data ──> Interpolated Data ──> Graphical plot
          │
          └──> Data you need

Instead, you are trying to get data back from graphics. This is wrong. Graphics should be write-only.

—SA

Posted 5-Oct-15 19:05pm

Sergey Alexandrovich Kryukov

Comments

Member 12035385 8-Oct-15 0:23am

As i said there are 10 known points. i am fitting a cubic spline through these points. how can i get coordinates of other points from the interpolated curve?

Sergey Alexandrovich Kryukov 8-Oct-15 2:45am

I already answered. The rest depends on your detail. You did not even specify the language, just listed three...
—SA

Member 12035385 13-Oct-15 23:01pm

I am currently using matlab. Planning to use python in future if time permits. The solution u mentioned is perfect. That is what i need. To be frank i am new to this area. So i dont have much idea about interpolation. After reading few book i decided to try with cubic spline. My main concern is the point coordinates. IS there any way to get the point data as a matrix output. i am unable to do it. If needed i can provide details about 10 data points.

Sergey Alexandrovich Kryukov 13-Oct-15 23:14pm

Sorry, I don't understand what you are missing. If you already use some interpolation algorithm, it gives you the points...
—SA