28.3.13 Lorentz2D

Function

z=z_0+\frac A{\left[ 1+\left( \frac{x-x_c}{w_1}\right) ^2\right] \left[ 1+\left( \frac{y-y_c}{w_2}\right) ^2\right] }

Brief Description

Non-linear Sigmoid (Logistic Cumulative) Function

Sample Curve

Image054.gif

Parameters

Number: 6

Name: Meanings: Lower Bounds: Upper Bounds:

z_0

z offset

A

height

x_c

x center

w_1

x width

w_1>0

y_c

y center

w_2

y width

w_2>0

Derived Parameters

FWHM_x=2w_1

FWHM_y=2w_2

Volume=Aw_1w_2\pi^2

Script Access

Function File

fitfunc\Lorentz2D.fdf