Picard Iteration Calculator

Solve Picard iteration steps for initial value problem models. Review convergence, errors, and estimate changes. Export clean tables for study, reports, homework, and checks.

Calculator

Formula Used

The initial value problem is written as y' = f(x,y), with y(x0) = y0.

Picard iteration rewrites it as y(n+1)(x) = y0 + integral from x0 to x of f(t, y(n)(t)) dt.

This calculator starts with y(0)(x) = y0. It then estimates each integral on a grid by the selected rule.

How to Use This Calculator

  1. Enter the derivative expression with x and y.
  2. Enter the starting point x0 and y0.
  3. Set the target x, step size, and maximum iterations.
  4. Choose an integral rule for the numerical approximation.
  5. Add an exact solution when you want error values.
  6. Press calculate, then review the result above the form.
  7. Use the CSV or PDF buttons to save the table.

Example Data Table

Derivative x0 y0 Target x Step Iterations Rule Note
x + y 0 1 1 0.1 5 trapezoid 2e^x - x - 1
x^2 - y 0 1 1 0.2 6 midpoint model check
sin(x) + y 0 0 1.5 0.15 7 trapezoid growth curve

Understanding Picard Iteration

Picard iteration is a fixed point method for initial value problems. It builds a solution curve by repeating an integral equation. The first curve is often a flat line through the starting value. Each new curve uses the previous curve inside the derivative function. This process can reveal how a solution grows, falls, or bends over an interval.

Why This Calculator Helps

Manual Picard work can become long. The derivative may contain x, y, powers, roots, or trigonometric terms. A table makes every step easier to inspect. This calculator uses a grid based numerical form of the Picard integral. It shows the final approximation, change between iterations, and optional exact error. You can test step size, integration style, tolerance, and iteration count.

Numerical Approach

The tool does not try to produce a symbolic polynomial. Instead, it evaluates the integral on small subintervals. The previous approximation supplies y values on the grid. The selected rule estimates each small area. Smaller steps usually improve the curve, but they also increase rows. More iterations may improve convergence until changes become small.

Good Input Choices

Start with a simple derivative. Use x and y as variables. Use expressions such as x+y, x^2-y, sin(x)+y, or exp(x)-y. Choose a step that reaches the target point with enough detail. Use a modest iteration count first. Then raise it when the maximum change stays large.

Reading the Output

The iteration summary shows the final value after each pass. The maximum change helps judge convergence. A small value means the new curve barely changed. The grid table shows the approximate solution at each x point. If you enter an exact solution, the table also displays absolute error.

Practical Uses

Picard iteration supports learning, checking, and reporting. It helps students see the link between differential equations and integral equations. It also helps teachers prepare examples. Engineers and analysts can use it for quick exploratory checks. Results should still be reviewed. Numerical settings always affect accuracy. Try several step sizes before trusting a final value.

Reporting

Use the exported files to compare runs. Keep the same equation. Change only one setting at a time. That habit makes numerical behavior easier to explain and repeat.

FAQs

What is Picard iteration?

Picard iteration is a method that solves an initial value problem by repeated integral updates. Each new approximation uses the previous approximation inside the derivative function.

What expression format can I use?

Use x and y as variables. Operators include +, -, *, /, and ^. Functions include sin, cos, tan, exp, log, sqrt, abs, and related common functions.

Why does step size matter?

Step size controls grid spacing. A smaller step usually gives a more detailed integral estimate. It also creates more rows and may need more processing time.

Which integral rule should I choose?

The trapezoid rule is a good default for balanced accuracy. Midpoint is also useful. Left and right rules are simpler and can show how estimates change.

What does maximum change mean?

Maximum change is the largest difference between two consecutive approximations on the grid. Smaller values suggest that the iteration is stabilizing.

Can I compare with an exact solution?

Yes. Enter an exact y(x) expression. The calculator evaluates it at each x value and shows the absolute error beside the approximation.

Why did the calculator stop early?

It stops early when the maximum change is less than or equal to the tolerance. That means the selected convergence limit was reached.

Are the results symbolic?

No. The calculator gives numerical Picard approximations on a grid. It is designed for tables, convergence checks, exports, and practical reporting.

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