Non linear curve If there are set of points (16.26,1000) (8.814,2000) (6.06,3000) (4.602,4000) in a similar way
if you plot these points in matlab you will get a nonlinear curve. After getting that curve, how to find equation for that given curve.
Please send me the answer as soon as possible.
 A: Suppose you use this to make your plot: 
x = [16.26 8.814 6.06 4.602];
y = [1000 2000 3000 4000];
plot(x,y);

The line that Matlab will plot has a very simple formula, it is just the line that uses piecewise linear interpolation to connects the dots.
If you want to find fitting solutions i recommend you to type help fit
A: I do not know Matlab but, if I plot your data, the points really look to be along an hyperbole (this seems to be one of the simplest functions to be used). So, a possible formula could be $$y=\frac{a+bx}{x+c}$$ Using nonlinear regression, these data lead to $$y=\frac{19426.3 -193.937 x}{x+0.0302068}$$ which corresponds to a sum of squares equal to $23.0216$.
If you still look for a simpler model, you could observe that, if you plot $xy$ as a function of $x$, you almost have a straight line; this means that $$y=a+\frac{b}{x}$$ could be another model. Using linear regression, these data lead to $$y=\frac{19269.6}{x}-184.589$$ which corresponds to a sum of squares equal to $32.8626$. So, in spite of the small value of parameter $c$ in the first model, it plays a significant role on the sum of the squares of residuals.
