Description
factor = (1+annualFraction)^years; population = initialPopulation*factor; doublingYears = ln(2)/log1p(annualFraction).
Ecological growth and scaling models express a chosen relationship between population, area, body mass or occupied patches. Supplied rates and exponents are model assumptions; a finite step can leave the intended physical domain.
factor = (1+annualFraction)^years; population = initialPopulation*factor; doublingYears = ln(2)/log1p(annualFraction).
When to use this tool
Use Population Doubling Discrete Growth Factor when checking one declared ecological growth or scaling term.
How to use the tool and how it works
- Enter annualFraction, years, initialPopulation. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read factor, population, doublingYears. Use the output convention below.
Require positive annualFraction, nonnegative years and initialPopulation. factor = (1+annualFraction)^years; population = initialPopulation*factor; doublingYears = ln(2)/log1p(annualFraction).1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| annualFraction | Strictly positive annual discrete growth fraction, not percent or continuous rate. | Required. Finite number; strictly above 0. |
| years | Years | Required. Finite number; minimum 0. |
| initialPopulation | Initial Population | Required. Finite number; minimum 0. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| factor | Factor | Required. Finite number. |
| population | Population | Required. Finite number. |
| doublingYears | Doubling Years | Required. Finite number. |
{
"input": {
"annualFraction": 1,
"years": 3,
"initialPopulation": 100
},
"output": {
"factor": 8,
"population": 800,
"doublingYears": 1
}
}Limitations and assumptions
- Rate is a positive annual fraction, not percent or a continuous rate. Zero and declining rates are rejected; density dependence and biological viability are omitted.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use validated parameters, appropriate time steps and suitable data to assess a real population or extrapolation.
References
Similar or alternative tools
- Patch Colonization Extinction One Step Term
Apply one explicit Euler step of a supplied colonization-extinction occupancy model without clipping its result.
- Lotka Volterra Competition One Term
effectiveLoad = population+competitionCoefficient*competitor; growth = growthRate*population*(1-effectiveLoad/capacity).