how to curve fit a data file on Wolframalpha.com PRO

Questions
,
1

I have a data file with a large number of data points that I would like to curve fit, but every attempt plots just the input data and not the curve fits.

Presently my data is in a .txt file formated as such:

33, 34, 35, 36, 37, 38, 39, 40…

I attempted to select the uploaded file and type “fit” after it. “fit” is always ignored.

How can I curve fit this file using the inbuilt ‘FIT’ function on wolframalpha.com?

2

Can you modify this to work for your data?

In[1]:= data = Table[{x, x^2 + RandomReal[{-2, 2}]}, {x, -4, 4}] (*make up some data points*)

Out[1]= {{-4, 17.4655}, {-3, 9.35509}, {-2, 2.49318}, {-1, -0.0807469},
 {0, -0.417158}, {1, -0.0704794}, {2, 2.71172}, {3, 9.31136}, {4, 15.9621}}

In[2]:= parabola = Fit[data, {1, x, x^2}, x] (*fit a parabola to the data*)

Out[2]= -1.17073 - 0.0949574 x + 1.12112 x^2

In[3]:= Show[ListPlot[data], Plot[parabola, {x, -4, 4}]] (*overlay the parabola and the points to check*)

Out[3]= ...plot to see if it worked snipped...
3

Thank you Bill.

It looks like you are using Mathematica, and I am simply using WolframAlpha Pro. I should modify my post to specify that.

Cheers.

4

I believe there are limits on how large the input can be for some uses of WolframAlpha, but this is small enough to be accepted.

http://www.wolframalpha.com/input/?i=Fit%5B%7B%7B-4%2C+17.4%7D%2C%7B-3%2C9.3%7D%2C%7B-2%2C+2.4%7D%2C%7B-1%2C-0.08%7D%2C%7B0%2C-0.4%7D%2C%7B1%2C-0.07%7D%2C%7B2%2C2.7%7D%2C%7B3%2C9.3%7D%2C%7B4%2C15.9%7D%7D%2C%7B1%2Cx%2Cx%5E2%7D%2Cx%5D

5

I have approximately 1900 data points. Do you think that exceeds the limit?
I shall try with fewer points in the set and see if that works.

I am logging a temperature gradient on an electrically heated element and I really need the equations that fit the line. That is the only reason I purchased the subscription. If I can’t get it to do that I have no other use for WA at this time.

Thank you for all your help.

6

This

says there is a one megabyte upload file size limit.
This

shows all the file types it can understand.

So I am assuming it can handle your 1900 data points.
The only question will be how to format the file and how to tell
WolframAlpha Pro you want a fitted line and not some other unwanted calculation.

Strictly as a comparison, if you wanted to post your 1900 comma separated points
and check to see that the posting process didn’t appear to mangle any of your data
and state that those were y for x=0,x=1,x=2,…x=1900 then in a couple of seconds I’d
do a linear regression and post the result.