Power Series Calculator

Category: Calculus
- June 17, 2025
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Calculate, visualise, and analyse power series expansions of common functions. Power series are infinite sums that can represent a wide variety of functions in the form of Σ an(x-c)n from n=0 to ∞.

Point around which the series is expanded
Exponent for binomial series

Advanced Options

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Understanding Power Series

A power series is an infinite sum of terms where each term has a specific power of the variable. These series are fundamental in calculus and are used to represent functions, solve differential equations, and perform numerical computations.

Key Concepts
  • Power Series: An expression of the form Σ an(x-c)n where c is the center of expansion.
  • Radius of Convergence: The range of x values for which the series converges.
  • Maclaurin Series: A special case of Taylor series centred at c = 0.
  • Taylor Series: A representation of a function as an infinite sum of terms calculated from the values of its derivatives at a single point.
  • Term-by-Term Operations: Power series can be differentiated and integrated term by term within their radius of convergence.
Common Power Series
Exponential:
ex = Σ xn/n! = 1 + x + x2/2! + x3/3! + ...
Sine:
sin(x) = Σ (-1)nx2n+1/(2n+1)! = x - x3/3! + x5/5! - ...
Cosine:
cos(x) = Σ (-1)nx2n/(2n)! = 1 - x2/2! + x4/4! - ...
Logarithm:
ln(1+x) = Σ (-1)n+1xn/n = x - x2/2 + x3/3 - ...
Applications of Power Series
  • Function Approximation: Computing values of complex functions to high precision.
  • Differential Equations: Solving differential equations that don't have closed-form solutions.
  • Physics: Modelling systems where simplified linear approximations are insufficient.
  • Computer Science: Calculating advanced mathematical functions efficiently in software.
  • Engineering: Approximating complex systems and analysing behaviour near critical points.

Disclaimer: This calculator provides approximate results based on truncated series. The accuracy depends on the number of terms used and the evaluation point's proximity to the center of expansion. For points outside the radius of convergence, results will be inaccurate.

Power series take the form:
Σ an(x - c)n from n = 0 to ∞

where an are coefficients and c is the centre of expansion.

What Is the Power series calculator?

The Power Series Calculator is an interactive tool that lets you compute and explore power series expansions of well-known mathematical functions like ex, sin(x), ln(1+x), and others. It helps you approximate functions using polynomial terms, visualise convergence, and understand how closely the series matches the actual function within a given range.

How This Calculator Helps You

Whether you’re a student learning Calculus or someone exploring advanced Math concepts, this tool can help you:

  • Understand the behaviour of functions near specific points using Taylor or Maclaurin series.
  • Estimate values of functions when exact forms are hard to evaluate.
  • Visualise how many terms are needed for an accurate approximation.
  • Compare the original function against its series form on a graph.
  • Analyse convergence and estimate potential errors in approximation.

It works especially well when paired with Other resources like the Limit Calculator, Second Derivative Calculator, or Quadratic Approximation Calculator for deeper mathematical insights.

How to Use the Calculator

Follow these steps to explore any function's power series:

  1. Select a Function: Choose from a list like exponential, sine, cosine, logarithmic, or enter a custom series.
  2. Set the Centre (c): This is the value around which the series expands.
  3. Choose Number of Terms: Higher values give better accuracy but may take longer to compute.
  4. Specify Evaluation Point: Enter the value of x where you want to estimate the function using the series.
  5. Use Advanced Options: Change decimal places, graph interval, and enable options like derivative calculations or convergence analysis.
  6. Click Calculate: See the formula, approximation value, error margin, and dynamic graph updates instantly.

Key Features

Why Power Series Are Useful

Power series let us break down complicated functions into simple polynomials, making them easier to analyse or approximate. They are essential in calculus, differential equations, and numerical methods. Applications include:

  • Solving differential equations (compare with Differential Equation Calculator).
  • Approximating function values in Physics and engineering.
  • Understanding local function behaviour using derivative analysis.
  • Exploring function limits and continuity (Limit Calculator support).

Frequently Asked Questions

What functions can I expand?
You can choose from a list of built-in functions or type your own custom power series format.

What is the centre of a series?
The centre (c) is the value around which the series is built. Changing it adjusts how the approximation behaves.

What does the “Number of Terms” control?
It sets how many terms the tool uses to build the polynomial. More terms generally mean better accuracy.

Can I find derivatives too?
Yes. You can calculate and view first and second derivatives using the built-in differentiation option, similar to a Derivative Calculator.

Does the tool show convergence?
Yes. You can check if your chosen point lies within the interval where the series is valid. This helps prevent misleading results, just like an Interval of Convergence Calculator.

Is this only for Taylor series?
It includes Taylor and Maclaurin series as well as geometric and binomial series. You can also enter custom series manually.

Final Tip

For a complete experience, use this calculator alongside other tools such as a limit solver, nth Derivative Calculator, or Antiderivative Finder. This helps build a better understanding of calculus as a whole.