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SRichards1

Contents

Function

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

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

Brief Description

Sigmoidal Richards function, type 1.

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

Sample Curve

Image:CFF Image476.jpg

Parameters

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_srichards1(x,a,xc,d,k)

Function File

FITFUNC\SRICHAR1.FDF

Category

Growth/Sigmoidal