Laplace Transform Calculator

The Laplace transform is a powerful mathematical tool that converts a time-domain function into its frequency-domain representation. This transformation simplifies the analysis of differential equations, making it especially useful in engineering, control theory, and signal processing.

Last Updated: April 13, 2025

What Is the Laplace Transform?

The Laplace transform is a mathematical operation that transforms a function of time into a function of complex frequency. It helps to convert calculus-heavy differential equations into simpler algebraic expressions. This technique is a cornerstone in control systems, electronics, mechanical engineering, and applied mathematics.

Formal Definition

\( \mathcal{L}\{f(t)\} = F(s) = \int_0^\infty e^{-st} f(t)\, dt \)
where:

  • f(t): the original time-domain function
  • F(s): the frequency-domain representation
  • s: a complex number, s = \sigma + j\omega

Why It Matters

  • 🔄 Transforms time-based behavior into frequency analysis
  • ⚡ Simplifies complex calculus into basic algebra
  • 📐 Widely used across engineering disciplines

Real-Life Analogy

Imagine trying to untangle a knot (your differential equation) by hand—it’s slow and tricky. The Laplace transform is like using a specialized tool to loosen the knot, making the problem easier to handle. Once solved, the inverse Laplace transform brings the answer back to its original form.

Applications of Laplace Transform

  • 🔌 Electrical Engineering – RLC circuit analysis
  • ⚙️ Mechanical Engineering – Vibration and motion equations
  • 📊 Control Systems – System stability and feedback design
  • 📡 Signal Processing – Filter and transform signals
  • 📘 Math & Physics – PDEs and initial value problems

How to Use the Laplace Transform Calculator

  1. Enter the function f(t) in the input box
  2. Select the time variable (default is t)
  3. Click "Calculate"
  4. View the result in F(s) format with step-by-step working

Pro tip: Use this calculator to verify manual calculations or explore new transform ideas.

Common Laplace Transform Table

f(t) F(s)
1 1 / s
t 1 / s²
tⁿ n! / sⁿ⁺¹
eat 1 / (s - a)
sin(bt) b / (s² + b²)
cos(bt) s / (s² + b²)
eat·sin(bt) b / [(s - a)² + b²]
eat·cos(bt) (s - a) / [(s - a)² + b²]

Laplace Transform Examples

  • f(t) = t² → \( \mathcal{L}\{t^2\} = \frac{2}{s^3} \)
  • f(t) = e-2t → \( \frac{1}{s + 2} \)
  • f(t) = sin(3t) → \( \frac{3}{s^2 + 9} \)
  • f(t) = e-t·cos(4t) → \( \frac{s + 1}{(s + 1)^2 + 16} \)

FAQ

What is a Laplace transform?

The Laplace transform is a mathematical technique used to convert a time-domain function into a complex frequency-domain function. It is commonly used to simplify differential equations in engineering and physics.

How do you calculate a Laplace transform?

To compute the Laplace transform of a function f(t), use the formula: \( \mathcal{L}\{f(t)\} = \int_0^\infty f(t)e^{-st} dt \), where s is a complex variable. Many functions have standard Laplace transform pairs that simplify the process.

What is the Laplace Transform used for?

The Laplace transform is mainly used to simplify and solve linear differential equations by converting them from the time domain to the frequency domain. It is widely applied in control systems, circuit design, and signal processing.

Is the Laplace transform reversible?

Yes, using the inverse Laplace transform, one can convert a function from the frequency domain back to the time domain. This is essential in practical applications after solving equations in the Laplace domain.

What’s the difference between Laplace and Fourier transforms?

The Laplace transform works for a broader class of functions, including those that grow exponentially. Fourier transforms are generally used for analyzing periodic signals, while Laplace transforms handle both transient and steady-state behaviors.

Ready to simplify your equations?

Try our free Laplace Transform Calculator and see your results instantly. Learn with step-by-step solutions and transform tables.

Start Calculating Now