30.1.58 ExpGro3

Function

$y=y_0+A_1e^{x/t_1}+A_2e^{x/t_2}+A_3e^{x/t_3}$

Three-phase exponential growth function with time constant parameters.

Number: 7

Names: y0, A1, t1, A2, t2, A3, t3

Meanings: y0 = offset, A1 = amplitude, t1 = time constant, A2 = amplitude, t2 = time constant, A3 = amplitude, t3 = time constant

Lower Bounds: none

Upper Bounds: none

Note: different initial parameters are used for t1, t2 and t3 so as to make sure t3 > t2 > t1 in the fitting results.

Individual growth rate:

k1 = 1/t1

k2 = 1/t2

k3 = 1/t3

Individual doubling time:

Td1 = t1*ln(2)

Td2 = t2*ln(2)

Td3 = t3*ln(2)

nlf_expgro3(x,y0,A1,t1,A2,t2,A3,t3)

FITFUNC\EXPGRO3.FDF