Calculator Input
Example Data Table
This sample uses the logistic map with x(0) = 0.25, r = 3.2, and K = 1.
| Step | x(n) | Formula | x(n+1) |
|---|---|---|---|
| 0 | 0.250000 | 3.2 × 0.25 × (1 - 0.25 / 1) | 0.600000 |
| 1 | 0.600000 | 3.2 × 0.60 × (1 - 0.60 / 1) | 0.768000 |
| 2 | 0.768000 | 3.2 × 0.768 × (1 - 0.768 / 1) | 0.570163 |
Formula Used
A discrete system follows the recursive rule x(n+1) = f(x(n)).
Supported formulas
- Linear affine:
x(n+1) = a × x(n) + b - Logistic:
x(n+1) = r × x(n) × [1 - x(n) / K] - Exponential:
x(n+1) = g × x(n) - Beverton-Holt:
x(n+1) = R × x(n) / [1 + ((R - 1) × x(n) / K)] - Ricker:
x(n+1) = x(n) × exp(r × [1 - x(n) / K]) - Quadratic:
x(n+1) = a × x(n)^2 + b × x(n) + c
Stability test
The calculator estimates the derivative near the final value. If |f'(x)| < 1, the point is usually locally stable. If |f'(x)| > 1, it is usually locally unstable.
Fixed point residual
The residual is |f(x_final) - x_final|. A smaller residual means the final value is closer to a fixed point.
How to Use This Calculator
- Select the system model that matches your problem.
- Enter the starting value, written as x(0).
- Set the needed model parameters.
- Choose the number of iterations.
- Set transient steps if early values should be ignored.
- Use bounds when your model must stay inside limits.
- Press the calculate button.
- Review the summary, table, stability, and period result.
- Download CSV or PDF when you need a saved report.
Discrete Dynamical System Guide
Step Based Modeling
A discrete dynamical system studies change step by step. It does not use continuous time. It moves from one state to the next by a rule. That rule is often written as x next equals f of x. The calculator above turns that idea into a clear table.
Where These Systems Appear
These systems appear in population models, finance, ecology, inventory planning, games, and scheduling. A small rule can create simple growth. It can also create oscillation, cycles, or chaotic looking behavior. For this reason, the first values matter. The chosen parameters also matter.
Model Choices
The tool supports several common maps. A linear map is useful for steady trend analysis. A logistic map is useful when growth slows near a capacity. The Ricker and Beverton-Holt maps are common in population work. The quadratic map helps explore nonlinear feedback. Each model creates a sequence from the starting value.
Advanced Options
Advanced options help with deeper checks. You can set the number of steps. You can ignore early transient values. You can select decimal precision. You can choose a tolerance for fixed point and cycle tests. Bounds are also included for safe modeling when values must stay inside a practical range.
Reading the Results
The result section shows the last value, total change, residual, local derivative, stability label, and detected period. The residual compares the final state with the next predicted state. A small residual means the sequence is close to a fixed point. The derivative estimate gives a local stability clue. When its absolute value is below one, nearby values usually move toward the point.
Cycle Detection
Cycle detection compares recent repeated blocks. It is a numerical test, not a formal proof. Use a smaller tolerance for strict checks. Use a larger tolerance when rounded data or noisy estimates are involved.
Exporting and Reviewing
The iteration table is useful for reports. It shows each current value, next value, change, and relative change. You can export this table as CSV for spreadsheets. You can also create a simple PDF for sharing. Always review units and assumptions before using results for decisions. For best results, compare several parameter sets, inspect early jumps, and validate the chosen map against real observations, not only a final number alone in practice.
FAQs
What is a discrete dynamical system?
It is a model where each new value is calculated from the previous value. The rule is repeated step by step. It is useful when change happens in rounds, periods, generations, turns, or cycles.
What does x(0) mean?
x(0) is the starting value of the system. Every later value depends on it. Changing x(0) can change the full sequence, especially in nonlinear models.
Which model should I choose?
Use the linear model for simple trends. Use logistic, Ricker, or Beverton-Holt maps for limited growth. Use the quadratic map when feedback is nonlinear and exploratory behavior is needed.
What is a fixed point?
A fixed point is a value that stays unchanged after applying the rule. In formula form, it satisfies x = f(x). The calculator estimates this using the final residual.
What does local stability mean?
Local stability means nearby values tend to move toward a point after repeated steps. The calculator estimates this with a numerical derivative near the final value.
What is a cycle?
A cycle happens when the sequence repeats after several steps. A period two cycle repeats every two steps. The calculator searches recent values for short repeating patterns.
Why use transient steps?
Early values may not show the long term pattern. Ignoring transient steps helps cycle detection focus on later behavior. This is useful for oscillating or settling systems.
Can I export the results?
Yes. Use the CSV button for spreadsheet work. Use the PDF button for a simple printable report. Both options use the iteration table shown after calculation.