Interpolation - it's just finding middleware, unknown value (numbers) Y1 at a known number of X1 within the limits certain boundaries (X0...Xn) && (Y0...Yn), where each X value is associated with the value ofУ.
It is not clear that such interpolation? Let me explain simply an example:
Imagine that you need to run a distance of 10 (km) (10 → 0)! Here you come to the starting line and start to run the race! Immediately from the start you ran at a speed 18 (km/hr). That you run, run and your speed gradually and evenly falls in overcoming distance. You run up to the finish line 0 (km) and cross it at a speed of already 3 (km/hr).
And you began to wonder what was your speed by 5 (km) from the finish? Can all known data presented in the form table below:
|x0 = 10||y0 = 18|
|x1 = 5||y1 = ?|
|xn = 0||yn = 3|