Re: How to interpolate this curve?

"Linus Utopia" wrote...
> How to interpolate this curve?
>
> Hi all,
>
> Please take a look at the following plot:
>
> http://img63.imageshack.us/img63/5599/gggyf5.jpg
>
> There are two curves:
>
> The red one is the ideal one and the blue one is the
> real data from experiments.
>
(snip)

> 1. Is there a symtematic method to detect the turning
> point starting from which the real curve begins to stray
> away from the ideal curve (here is x=15)?

The ideal curve has a constantly decreasing positive slope.
I don't know how evenly-spaced or noisy your data is, but
use your favorite method for calculating the second derivative
and truncate the data before it inflects.

- Brian