28.1.57 ExpGro2

Function

y=y_0+A_1e^{x/t_1}+A_2e^{x/t_2}

Brief Description

Two-phase exponential growth function with time constant parameters.

Sample Curve

ExpGro2 FitFunc.png

Parameters

Number: 5

Names: y0, A1, t1, A2, t2

Meanings: y0 = offset, A1 = amplitude, t1 = time constant, A2 = amplitude, t2 = time constant

Lower Bounds: none

Upper Bounds: none

Note: different initial parameters are used for t1 and t2 so as to make sure t2 > t1 in the fitting results.

Derived Parameters

Individual growth rate:

k1 = 1/t1

k2 = 1/t2

Individual doubling time:

tau1 = t1*ln(2)

tau2 = t2*ln(2)

Script Access

nlf_expgro2(x,y0,A1,t1,A2,t2)

Function File

FITFUNC\EXPGRO2.FDF

Category

Exponential