释义 |
Population GrowthThe differential equation describing exponential growth is
| (1) |
This can be integrated directly
| (2) |
| (3) |
Exponentiating,
| (4) |
Defining gives in (4), so
| (5) |
The quantity in this equation is sometimes known as the Malthusian Parameter.
Consider a more complicated growth law
| (6) |
where is a constant. This can also be integrated directly
| (7) |
| (8) |
| (9) |
Note that this expression blows up at . We are given the Initial Conditionthat , so .
| (10) |
The in the Denominator of (10) greatly suppresses the growth in the long runcompared to the simple growth law.
The Logistic Growth Curve, defined by
| (11) |
is another growth law which frequently arises in biology. It has a rather complicated solution for .See also Gompertz Curve, Life Expectancy, Logistic Growth Curve, Lotka-Volterra Equations,Makeham Curve, Malthusian Parameter, Survivorship Curve
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