Cross product of complex vectors

In summary, the cross product of complex vectors is calculated using the same formula as for real vectors, with the addition of taking the complex conjugate of the second vector. This results in a vector with components (a_y b_z - a_z b_y) for the x direction, (a_z b_x - a_x b_z) for the y direction, and (a_x b_y - a_y b_x) for the z direction. However, this definition may not be as intuitive as with real vectors, as the unit vectors x-cap, y-cap, and z-cap do not have a clear representation in the complex plane.
  • #1
GabDX
11
0
How is computed the cross product of complex vectors?

Let ##\mathbf{a}## and ##\mathbf{b}## be two vectors, each having complex components.
$$\mathbf{a} = a_x \mathbf{\hat{x}} + a_y \mathbf{\hat{y}} + a_z \mathbf{\hat{z}}$$
$$\mathbf{b} = b_x \mathbf{\hat{x}} + b_y \mathbf{\hat{y}} + b_z \mathbf{\hat{z}}$$
For example, the ##x## component of ##\mathbf{a}## could be ##a_x=3+4i##.

I know that the dot product of ##\mathbf{a}## and ##\mathbf{b}## is
$$\mathbf{a} \cdot \mathbf{b} = a_x b_x^* + a_y b_y^* + a_z b_z^*$$
where ##^*## denotes the complex conjugate. Is there some similar trick that should be done with the cross product of complex vectors or is it the same as with real vectors? In other words, is the cross product given by
$$\mathbf{a}\times\mathbf{b} = (a_y b_z - a_z b_y)\mathbf{\hat{x}}
+ (a_z b_x - a_x b_z)\mathbf{\hat{y}}
+ (a_x b_y - a_y b_x)\mathbf{\hat{z}}$$
or is it something different?
 
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  • #2
In such a vector definition, it is not clear what the unit vectors x-cap, y-cap, and z-cap would represent.

In standard complex variables, a complex function f(z) represents a mapping from the complex x,y plane to another complex u,v plane, in my understanding. Thus f(z) = f(x+iy) = u + iv.
 
  • #3
This question has been raised before. Google "cross product complex vectors".
 
  • #4
Raised but not answered!
 
  • #5


The cross product of complex vectors is computed in a similar way as with real vectors. The only difference is that the complex conjugate is taken for each component in the calculation. So the cross product of two complex vectors ##\mathbf{a}## and ##\mathbf{b}## is given by:

$$\mathbf{a}\times\mathbf{b} = (a_y b_z^* - a_z b_y^*)\mathbf{\hat{x}}
+ (a_z b_x^* - a_x b_z^*)\mathbf{\hat{y}}
+ (a_x b_y^* - a_y b_x^*)\mathbf{\hat{z}}$$

This is because the cross product represents a vector perpendicular to both ##\mathbf{a}## and ##\mathbf{b}##, and the complex conjugate ensures that the resulting vector is also perpendicular in the complex plane. So the cross product of complex vectors is a useful tool in understanding the geometry of complex numbers.
 

What is the cross product of complex vectors?

The cross product of complex vectors is a mathematical operation that takes two complex vectors as input and produces a new complex vector as output. It is defined as the product of the magnitudes of the two vectors, multiplied by the sine of the angle between them, and rotated by 90 degrees in the direction perpendicular to both vectors.

How is the cross product of complex vectors different from the cross product of real vectors?

The main difference between the cross product of complex vectors and the cross product of real vectors is that the former produces a complex vector as output, while the latter produces a real vector. This means that the cross product of complex vectors takes into account the imaginary components of the vectors, while the cross product of real vectors only considers their real components.

What are the properties of the cross product of complex vectors?

The cross product of complex vectors has many of the same properties as the cross product of real vectors, including bilinearity, anticommutativity, and the fact that it is orthogonal to both input vectors. It also follows the right-hand rule, where the direction of the resulting vector is determined by curling the fingers of the right hand from the first vector to the second vector.

Can the cross product of complex vectors be used to find the area of a parallelogram?

Yes, the magnitude of the cross product of two complex vectors is equal to the area of the parallelogram formed by those vectors. This is a useful application of the cross product of complex vectors, as it allows us to find the area of a parallelogram in a complex plane without having to use the standard formula for the area of a parallelogram.

Are there any real-world applications of the cross product of complex vectors?

Yes, the cross product of complex vectors has many real-world applications, particularly in physics and engineering. It is used to calculate the torque on an object in motion, the magnetic field strength in electromagnetism, and the angular momentum of a rotating object. It is also used in computer graphics to calculate lighting and shading effects.

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