How can I do regression analysis in Sage?

Question

I tried this unsuccessfully:

find_fit(data, quadratic_residues)

I am trying to find the best-fit for data about water flow rates: http://dl.getdropbox.com/u/175564/rate.png

---edit after the comment---

The new code:

var('x')
model(x) = x**2
find_fit((xlist, reqlist), model)

The error message:

Traceback (click to the left for traceback)
...
TypeError: data has to be a list of lists, a matrix, or a numpy array

---edit

The error message is now:

Traceback (click to the left for traceback)
...
ValueError: each row of data needs 2 entries, only 5 entries given

The same here as a picture: http://dl.getdropbox.com/u/175564/sage.png

Answer 1

mydata = [[1,3],[2,7],[3,13],[4,24]]
var('a,b,c')
mymodel(x) = a*x^2 + b*x + c 
myfit = find_fit(mydata,mymodel,solution_dict=True)
points(mydata,color='purple') + plot(
  mymodel(
    a=myfit[a],
    b=myfit[b],
    c=myfit[c]
    ), 
    (x,0,4,),
    color='red'
  )