SRichards2

Contents

Function

y=a\left[ 1+\left( d-1\right) e^{-k\left( x-xc\right) }\right] ^{1/\left( 1-d\right) },d\neq 1

Brief Description

Sigmoidal logistic function, type 2.

Reference: Seber, G. A. F., Wild, C. J. 1989. Nonlinear Regression. John Wiley & Sons, Inc. pp. 332 - 337

Sample Curve

Image:CFF Image480.jpg

Parameter

Number: 4

Names: a, xc, d, k

Meanings: a = top asymptote, xc = center, d = unknown, k = coefficient

Lower Bounds: a > 0.0, k > 0.0

Upper Bounds: none

Script Access

 nlf_srichards2(x,a,xc,d,k)

Function File

FITFUNC\SRICHAR2.FDF

Category

Growth/Sigmoidal