A GUI Program for Function Fitting

This is a GUI for linear or nonlinear function fitting with one variable
Look at the Icon, the first two texts are used to input the data you want to process, the third is a basis function that you get from the data, in the above icon, I think the type of the function should be that,so do I.
what should we note is that the number of elements in the forth text needs to match the parameters number(such as a,b,c, and I give the initial value[.5, .5, .5])
and the the bold characters are results that Matlab calculates for target function(a = -0.023674, b = 0.47497, c = 4.1162) ,and then I get the concrete function. Below the figure , A value represents the mean square error, which is used to estimate the fitting quality, if it is so big, you are supposed to change the basis function or initial values.