## How do you do quaternion multiplication?

The multiplication rules for the imaginary operators are the same as for other numbers. We just put each quaternion in brackets and multiply out all the terms: (a + i b + j c + k d)*(e + i f + j g + k h). When we are multiplying the imaginary operators we use the following rules: i*i = j*j = k*k = -1.

## What does quaternion multiplication do?

The multiplication of quaternions represents composing the two rotations: perform one rotation and then perform the other one. It’s clear that this should represent a rotation (imagine rotating, say, a bowling ball in place).

**How do you convert a quaternion to a matrix?**

Combine the quaternion rotations into a single representation, then apply the quaternion rotation to arbitrarily initialized Cartesian points. Combine the rotation matrices into a single representation, then apply the rotation matrix to the same initial Cartesian points.

**How do you calculate quaternion?**

💡 Quaternions are expressions of the form q = a + b*i + c*j + d*k , where a , b , c , and d are arbitrary real numbers and i , j , and k are base elements sometimes called the basic unity quaternions.

### How do you make quaternions?

The unit quaternion can now be written in terms of the angle θ and the unit vector u = q/q: q = cos θ + usinθ.

### Do quaternions have zero divisors?

Quaternions are Not an Integral Domain, but have no zero-divisors.

**Where are quaternions used?**

Today, quaternions have applications in astronautics, robotics, computer visualisation, animation and special effects in movies, navigation and many other areas.

**How do you multiply matrices with NumPy?**

The following code shows an example of multiplying matrices in NumPy:

- import numpy as np.
- # two dimensional arrays.
- m1 = np. array([[1,4,7],[2,5,8]])
- m2 = np. array([[1,4],[2,5],[3,6]])
- m3 = np. dot(m1,m2)
- print(m3)
- # three dimensional arrays.

## How do you convert a 3×3 matrix to a rotation matrix?

The way I’ve been doing it is to use Singular Value Decomposition, so that M=U * S * V. transpose and then R=U * V. transpose.

## Can you multiply a vector by a quaternion?

As for the multiplication with a vector, you just extend the vector to a quaternion by setting a quat’s real component to zero and its ijk components to the vector’s xyz. Then you do the quaternion multiplications to get v’, and then extract the ijk components again.