Covariance Matrix
Given 
sets of variates denoted 
, ..., 
, the first-order covariance matrix is defined by
where
is the Mean. Higher order matrices are given by
An individual matrix element
is called the Covariance of 
and 
.See also Correlation (Statistical), Covariance, Variance- Periapsis
- Perigon
- Perimeter
- Perimeter Polynomial
- Period Doubling
- Periodic Function
- Periodic Point
- Periodic Sequence
- Period Three Theorem
- Perkins' Quilt
- Perko Pair
- Permanence of Algebraic Form
- Permanence of Mathematical Relations Principle
- Permanent
- Permil
- Permutation
- Permutation Group
- Permutation Matrix
- Permutation Pseudotensor
- Permutation Symbol
- Permutation Tensor
- Peron Integral
- Perpendicular
- Perpendicular Bisector
- Perpendicular Foot