Gamma Function Calculator

Calculate gamma function values with high precision for real and complex numbers

Calculate Gamma Function

Argument Type

Examples: 5, 2.5, -1.5, 0.5

Gamma Function Result

Input
z = 1
Γ(z)
1.0000
Method
Exact Formula
Precision
5 significant figures

Step-by-Step Solution

Input: z = 1
Positive integer: Γ(1) = (1-1)! = 0!
0! = 1
Therefore: Γ(1) = 1

Common Gamma Function Values

Positive Integers

Γ(1) = 0! = 1

Γ(2) = 1! = 1

Γ(3) = 2! = 2

Γ(4) = 3! = 6

Γ(5) = 4! = 24

Half-Integers

Γ(1/2) = √π ≈ 1.7725

Γ(3/2) = (1/2)√π ≈ 0.8862

Γ(5/2) = (3/4)√π ≈ 1.3293

Γ(7/2) = (15/8)√π ≈ 3.3234

Negative Half-Integers

Γ(-1/2) = -2√π ≈ -3.5449

Γ(-3/2) = (4/3)√π ≈ 2.3633

Γ(-5/2) = -(8/15)√π ≈ -0.9453

Key Properties

1

Factorial Relation

Γ(n) = (n-1)! for positive integers

2

Functional Equation

Γ(z+1) = z × Γ(z)

3

Special Value

Γ(1/2) = √π

4

Reflection Formula

Γ(z)Γ(1-z) = π/sin(πz)

Quick Tips

Poles: Γ(z) is undefined at z = 0, -1, -2, -3, ...
Positive integers: Use factorial relationship for exact values
Half-integers: Can be expressed in terms of √π
Large values: Use Stirling's approximation for efficiency

Understanding the Gamma Function

What is the Gamma Function?

The Gamma function Γ(z) is a generalization of the factorial function to real and complex numbers. It extends the concept of n! to non-integer values, providing a continuous interpolation of the factorial.

Mathematical Definition

For complex numbers with positive real parts, the Gamma function is defined by the integral:

Γ(z) = ∫₀^∞ t^(z-1) e^(-t) dt

Applications

Statistics & Probability

Used in gamma distribution, beta function, and various statistical models

Physics

Appears in quantum mechanics, thermodynamics, and special relativity

Number Theory

Connected to Riemann zeta function and analytic number theory

Approximation Methods

L

Lanczos Approximation

High accuracy for moderate values

S

Stirling's Approximation

Efficient for large arguments

N

Nemes' Approximation

Simple formula with good accuracy