To Exponentially fit a given set of data points.
[yfit,a,c]=expofit(x,y)
an array of x axis points
an array of y axis points
an array that contains the fitted points
coefficient of e^ax
coefficient of x such that y=c*e^(a*x)
Returns the fitted data points, coefficients a and c such that y=c*exp(a*x) is the fitted curve.