Quaternions, how to prove q^** = q

In summary, quaternions are a four-dimensional hypercomplex number system that extends the complex numbers and is useful in fields such as physics, engineering, and computer graphics. They represent rotations in three-dimensional space more efficiently than matrices and have the unique property of being equal to their own conjugate. This property can be proven by using the definition of the conjugate or by showing it is equal to the quaternion multiplied by its inverse. However, this property is unique to quaternions and cannot be extended to other hypercomplex number systems.
  • #1
hsong9
80
1

Homework Statement


quaternion q = a + bi + cj + dk
conjugate q* = a - bi - cj - dk

I do not know how I get (q*)* = q



The Attempt at a Solution

 
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  • #2


a, b, c and d are real, aren't they? Just take the double conjugate.
 
  • #3


a,b,c, and d are real.
so just..
show that (q*)* = q
(a + bi + cj + dk)* = a - bi - cj - dk and
(a - bi - cj - dk)* = a + bi + cj + dk Complete.
is it enough?
 
  • #4


I can't think of anything I'd add.
 

FAQ: Quaternions, how to prove q^** = q

What are quaternions and how are they different from other number systems?

Quaternions are a type of hypercomplex number system that extends the complex numbers. They are composed of four components - a real part and three imaginary parts. Unlike complex numbers, which have only one imaginary part, quaternions have three, making them a four-dimensional system. This allows for more complex calculations and is useful in fields such as physics, engineering, and computer graphics.

How do quaternions represent rotation in three-dimensional space?

In three-dimensional space, rotations can be represented using a three-by-three matrix. Quaternions can also represent these rotations using four components, making them more efficient for calculations. The rotation can be represented by the imaginary components of the quaternion, while the real component remains unchanged. This allows for easier manipulation and interpolation of rotations.

What is the significance of q^** = q in quaternions?

In quaternions, q^** represents the conjugate of q. It is obtained by changing the sign of the imaginary components of q. The equation q^** = q is significant because it shows that a quaternion is equal to its own conjugate. This is a fundamental property of quaternions and is used in many of their calculations.

How can you prove that q^** = q for any quaternion q?

One way to prove this property is by using the definition of the conjugate of a quaternion - changing the sign of the imaginary components. By doing this, you can expand q^** and q and show that they are equal. Another approach is to use the fact that the conjugate of a quaternion is equal to its inverse, and then show that q^** is equal to q multiplied by its inverse, resulting in q^** = q.

Can the property q^** = q be extended to other hypercomplex number systems?

No, the property q^** = q is unique to quaternions and cannot be extended to other hypercomplex number systems. This is because other systems, such as octonions or sedenions, have different properties and operations that do not follow the same rules as quaternions. However, some of the concepts and operations used in proving q^** = q may be applicable to other number systems as well.

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