# Monthly Archives: April 2020

## What Is Rounding?

Rounding is the transformation of a number expressed in a particular base to a number with fewer digits. For example, in base 10 we might round the number to , which can be described as rounding to three significant digits … Continue reading

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## What Is a Random Orthogonal Matrix?

Various explicit parametrized formulas are available for constructing orthogonal matrices. To construct a random orthogonal matrix we can take such a formula and assign random values to the parameters. For example, a Householder matrix is orthogonal and symmetric and we … Continue reading

## What Is a Correlation Matrix?

In linear algebra terms, a correlation matrix is a symmetric positive semidefinite matrix with unit diagonal. In other words, it is a symmetric matrix with ones on the diagonal whose eigenvalues are all nonnegative. The term comes from statistics. If … Continue reading

## What Is a Hadamard Matrix?

A Hadamard matrix is an matrix with elements and mutually orthogonal columns. For example, is a Hadamard matrix. A necessary condition for an Hadamard matrix to exist with is that is divisible by , but it is not known if … Continue reading