[Math] Rate of Convergence vs Radius of Convergence

convergence-divergencefibonacci-numbers

What is the difference between finding the 'rate of convergence' and the radius of convergence'? The question I am trying to solve here is to find the rate of convergence of the ratio of Fibonacci which is $\frac{F_{n+1}}{F_n}\to \phi$. Can someone guide me to how I would find the rate of convergence of this? And also tell me what the difference between radius and rate is?

Edit: I understand the difference, but I need help finding the rate of convergence of the ratio of Fibonacci which is $\frac{F_{n+1}}{F_n}\to\phi$

Best Answer

Lets take for example the geometric sequence,

$$a_n=a_0q^n$$

The Rate of convergence is $q$

And the Radius of convergence is the values of $q$ for which: $$a_0\sum_{i=0}^{\infty}{q^i}<\infty$$ The radius in this case is $$-1<q<1$$

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