SRichards1

Contents 1 Function 2 Brief Description 3 Sample Curve 4 Parameters 5 Script Access 6 Function File 7 Category

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

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

Function File

FITFUNC\SRICHAR1.FDF

Category

Growth/Sigmoidal