Find a a value from a graph that is not in the array using reciprocal fit

This is my code. So I plotted t1 and n and now I need to find the reciprocal and with the reciprocal find the t1 value of n=0.653. But at the end I am just getting an empty array.

t1= [6.22 3.59 2.68 2.53 2.19 1.82];

n= linspace(0.60,0.70,6);

plot(n,t1,"g")

hold on

p= polyfit(n,t1,1);

f1= polyval(1./p,n);

plot(n,f1)

index = find(n==0.653);

f1_point= f1(index);

Answer 1

[Torsten]

t1= [6.22 3.59 2.68 2.53 2.19 1.82];
n= linspace(0.60,0.70,6);
f1 = interp1(n,1./t1,0.653)

f1 = 0.3875