Transfer Function Poles and Zeros Calculator

Calculate zeros, poles, and basic stability for a second-order transfer function from numerator and denominator coefficients.

Engineering MathControl SystemsPoles and Zeros

Calculate

H(s) = (n₂s² + n₁s + n₀) / (d₂s² + d₁s + d₀)

n₂
n₁
n₀
d₂
d₁
d₀
Please enter valid values.

What this calculator teaches

A transfer function describes how an input signal becomes an output signal in the s-domain. Zeros come from the numerator and poles come from the denominator.

Poles are especially important because their real parts help determine stability and transient response.

Formula & Symbols

ConceptFormulaMeaning
Transfer functionH(s)=N(s)/D(s)Ratio of output to input in the s-domain.
ZerosN(s)=0Values of s that make the numerator zero.
PolesD(s)=0Values of s that make the denominator zero.
Stability ideaRe(poles)<0Continuous-time system is stable when all pole real parts are negative.

Step-by-Step Examples

Example 1
Simple zeros
  • N(s)=s²+3s+2.
  • Factor: (s+1)(s+2).
  • Zeros are -1 and -2.
✓ Zeros: -1, -2.

Where students use this

🎓
High school and college
Use the tool to check homework and understand each step.
📊
Data and modeling
Connect formulas to tables, graphs, and real values.
🧪
Science and engineering
Use math results inside physics, chemistry, and engineering problems.
💻
Computer science
Apply the same logic to algorithms, systems, and numerical work.

Common Mistakes to Avoid

⚠️
Calling zeros poles

Zeros come from the numerator; poles come from the denominator.

⚠️
Ignoring complex roots

Second-order systems often have complex-conjugate poles.

⚠️
Using numerator for stability

Stability depends primarily on pole locations, not zero locations.

Frequently Asked Questions

What is a pole?
A pole is a root of the denominator of the transfer function.
What is a zero?
A zero is a root of the numerator of the transfer function.
What makes a continuous-time system stable?
For a basic transfer-function model, all poles should have negative real parts.
Can poles be complex?
Yes. Complex poles often describe oscillatory behavior.

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Formula Explorer connections

Interpretation: This formula describes an algebraic relationship among variables, functions, equations, roots or sequences. Assumption: Respect the expression’s domain and excluded values. Check roots in the original equation because transformations can introduce extraneous solutions.

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