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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