Math Is Fun Forum

kappa_am

Member

Registered: 2013-12-20

Posts: 63

Curve fitting

Hi all;
I need to find a function that fit to all the obtained points. I used MATLAB curve fitting, and found some function. However there is a problem. Most of the proposed function by Matlab rapidly increases or decreases, while my other point which are not engaged in curve fitting are constant and equal to 1. I would be grateful if you suggest me a method to find a most suitable function.

The data is  as below:
x
55
65
75
85
95
105
115
125
135
145
155
165

Y

0.030
0.077
0.143
0.393
0.595
0.821
0.940
0.964
0.988
0.988
0.994
1.000

Thank you

Last edited by kappa_am (2015-05-19 22:23:03)

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Curve fitting

What kind of fit do you want? Least squares, minimax, fourier? Does that data come from some physical process?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

kappa_am

Member

Registered: 2013-12-20

Posts: 63

Re: Curve fitting

yes it comes from an experiment. least squares is ok.

thank you

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Curve fitting

You have how many points that are constant and equal 1?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

kappa_am

Member

Registered: 2013-12-20

Posts: 63

Re: Curve fitting

it steady on 1 after 165, I have examined over 10 points.

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Curve fitting

Do you want to include those points in your fit?

---

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.