finding a value of x for a given y

lets say i have x=[10:10:100];

y=[23 45 60 82 111 140 167 198 200 220];

and i want to use linear interpolation to approximate the value of x when y=80

i can use interp1(x,y,80) to find the value of y when x=80

how can i get the opposite??

Answer 1

[the cyclist]

interp1(y,x,80)

[taher elshreef]

cant believe i didnt think of that :)