Re: Some way to differentiate (1st order derivative)?

[Levente <ln...@dr...>]

On Mon, 2007-10-22 at 13:51 +0200, Juergen Wieferink wrote:

> There is a new assignment operator (and a comma operator), so you
> can plot something like:
>=20
> old_x =3D NaN
> plot 'test.dat' using 1:(dx=3D$1-old_x,old_x=3D$1,dx)
>=20

First of all, thanks to everybody who helped me! I succeeded in
approximating the differential of data files the following way, using
J=C3=BCrgen's example:

# Approximation of the first derivative of x-y data
# by the method: (y(n)-y(n-1))/(x(n)-x(n-1))

old_x =3D NaN
old_y =3D NaN
plot 'something.dat' using 1:(dx=3D$1-old_x,dy=3D$2-old_y,old_x=3D$1,old_y=
=3D
$2,dy/dx)

Just to let know to whom it may be useful. Maybe a small demo file could
be written to demonstrate its use (I am pleased to post such a demo if
this is OK).

Thanks again, folks!

Levente