I'm looking for a function that would recieve a set of data and would return the coefficent of a 3th degree polynome that match those data at best.
I'm able to do it with excel by ploting the value (x,y) and asking for a polynomial trendline of order 3. Then display the equation on the chart. I'm also able to use the LinEst function of Excel but now I would like to do it in Fortran.
I'm sure that there is already something out there that would do it. Any one know it ?