Fit is a front-end to Mathematica's least-squares fitting routine.

There are four main windows in the program.  They all appear in the Tools menu.  The titles of these windows are Data, Polynomial Fit, Graphs and Approximating Polynomial.

Data holds a matrix into which data will be typed or displayed.
Polynomial Fit is the main control window.
Graphs is where the data will be plotted where the approximating function 	will be graphed.
Approximating Polynomial is where the approximating polynomial will be 	displayed.

Data can be entered directly into the matrix in Data.  Alternatively, you can store data in a ascii file having the extension data.  The first item in the data file must be the number of pairs (points), followed by the data points.  A sample data file Sine.data is included.  Choosing Open from the File menu will bring up a panel from which you can select the data file, and then the data will be loaded into the matrix in Data.

Polynomial Fit allows you to specify the degree of the polynomial which will be fit to the data.  It also contains the controls which cause the approximating function to be computed, the data to be plotted (as points or connected by lines), the approximation to be graphed, and the data and approximation to be displayed at the same time.

The graphs will be displayed in Graphs.  Graphs can be sized to a larger size, but cannot be reduced smaller than its original size.

The approximating polynomial will be displayed in Approximating Polynomial.