Finding equation for regression curve

[canadiangoose]

Homework Statement

I want to know how to find equation for the interpolated function of any degree. On Mathematica, for example.

The Attempt at a Solution

Unfortunately, on Excel, the plots are deceiving because the points on the plot are actually out of range.

For example, this equation: - 0.037*Math.pow(i,5) + 0.857*Math.pow(i,4) - 8.406*Math.pow(i,3) + 32.33*Math.pow(i,2) - 46.68*i + 260.2

is displayed to be in the range of 0 and 255 between values 1 and 21 for i.

however, when plugging in numbers, values are clearly not in the range. you get a negative number for i =18.

So therefore, is there a more accurate way of finding regression curves for data AND the equation for the curve?

 

[The Electrician]

Are you trying to fit a polynomial to your data, or can you fit other equations?

How many data points do you have?

 

[whammy123]

use some software as Mathlab or Mathcad, find the algorythm for 'Polynomial Approxiamtion' and you will obtain approximating polynomial for given data (x and y values)