Fixed-Point Iteration Calculator

When to use

• Use this page when you need a transparent fixed-point iteration with update-size and residual monitoring..
• Use it to compare hand calculations, spreadsheet work, lecture examples, or early engineering-analysis estimates.
• Use it when you need visible steps and warnings rather than a single black-box answer.

How to use

1. Choose the numerical method or input mode when the tool provides options.
2. Enter the expression, matrix, table, tolerance, step size, or interval values requested by the form.
3. Click Run Fixed-Point Iteration to generate the estimate, table, visual, copy summary, and downloads.
4. If you change a relevant input after a successful run, rerun the calculation because stale results are hidden.

Inputs

Expression

A restricted math expression using allowed variables such as x, or x and y for ODE tools.

Tolerance or step size

A numeric control for convergence or discretization accuracy. Smaller values can improve accuracy but may increase roundoff or iteration cost.

Maximum iterations

A safety limit that prevents unbounded iteration when convergence is slow or impossible.

Matrix or table input

Rows are entered one per line with comma- or space-separated finite numeric values.

Precision

Controls displayed significant digits. Internal calculations keep unrounded JavaScript floating-point values.

Notation

Interpretation

• A converged result means the selected numerical stopping rule was satisfied; it does not prove that the mathematical model or input data are correct.
• Residuals, step sizes, bracket widths, and warnings should be reviewed together before using a result in engineering or research work.
• Matrix and table calculations can be sensitive to scaling, conditioning, spacing, and noisy input values.

Convergence and accuracy guidance

• Tight tolerances can expose floating-point roundoff; verify that the result remains stable when tolerance, step size, or starting guesses are changed.
• Root-finding methods depend on initial brackets, guesses, derivatives, or fixed-point mappings. A failed run often indicates a poor setup rather than a nonexistent solution.
• Interpolation, integration, differentiation, and ODE estimates depend strongly on smoothness and spacing. Use convergence checks or smaller steps where the function changes rapidly.

Worked examples

Assumptions

• Calculations use real finite numbers and standard double-precision floating-point arithmetic.
• The entered model, table, or matrix is assumed to represent the intended mathematical problem.
• No remote solver, AI API, database, or server-side numerical execution is used.

Practical guidance

• Start with simple benchmark problems before using a method on new engineering or research equations.
• Check the visual and iteration or sample table; they often reveal divergence, oscillation, extrapolation, or poor spacing.
• For final design decisions, compare with validated software, analytical solutions where available, and qualified professional judgment.

Common mistakes

• Using a rearrangement that is not contractive.
• Confusing small updates with a correct physical model.
• Forgetting to enter f(x) when residual checking is desired.

Limitations

• Convergence depends on g(x), not only on f(x).
• Oscillation or divergence can occur.
• The tool does not automatically find the best rearrangement.

Related workflow links