Given an equation and data points, find the best fit coefficients of the equation

I have a set of data points:

x=0:1:5;

y=[1 3 9 27 81 243];

and I need to determine the coefficients of the exponential sum of order one f (x) = which best approximates in the least squares sense the assigned data and the residual corresponding to it.

Shuld I use polyfit? I have no idea

Thank you in advance

Answer 1

[Torsten]

  x = 0:5;
  y = [1 3 9 27 81 243];
  A = [ones(6,1),exp(x.')];
  b = y.';
  a = A\b;
  f = @(x) a(1)+a(2)*exp(x);
  plot(x,[f(x);y])

"a" gives the coefficients of your equation:

a(1) = a0, a(2) = a1

[Ginevra cianci]

thank you so much!