What is a Linear Combination of Spherical Harmonics?

In summary, the conversation revolves around using spherical harmonics to fit a model to data. The main question is about the meaning of expressing everything as a "linear combination of spherical harmonics" and how to determine the coefficients for a first-order spherical harmonic. The speaker also mentions having trouble understanding the use of imaginary numbers in this context. They are seeking clarification and assistance in this topic.
  • #1
Fyrefly
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Okay, so I'm working on using spherical harmonics to fit a model to some data. The thing is, everything can apparently be described as a "linear combination of spherical harmonics" but nobody is explaining in plain English what that means, at least to me! :D

I see lots of double sum equations and everybody seems to solve spherical harmonics in a different way. So what I'd like to know, is this right? Based on the table of spherical harmonics I think a linear combination to get a 1st order spherical harmonic of them would look something like:

E(θ, [itex]\varphi[/itex]) = A*Y[0,0] + B*Y[-1,1] + C*Y[0,1] + D*Y[1,1].

So to fit my model I would need to determine coefficients A, B, C, and D. Is this right? Also, is there a particular way to do it for real-valued spherical harmonics? I don't have imaginary numbers in my data and this isn't a plotting exercise so I'm not sure what to do with them.
 
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  • #2
Did I put this in the wrong section? I'd love some help when someone can manage the time. Thanks.
 

Related to What is a Linear Combination of Spherical Harmonics?

1. What is a Linear Combination of Spherical Harmonics?

A linear combination of spherical harmonics is a mathematical expression that combines multiple spherical harmonics together to form a new function. This new function retains the properties of the individual spherical harmonics, but may have different coefficients and may be defined over a different domain.

2. What are spherical harmonics?

Spherical harmonics are a set of special functions that are defined on the surface of a sphere. They are used to represent functions that have spherical symmetry, such as the gravitational or electric potential of a spherical mass or charge distribution.

3. How are spherical harmonics related to spherical coordinates?

Spherical harmonics are closely related to spherical coordinates, which are a system of coordinates used to define points on the surface of a sphere. The spherical harmonics are functions of the angles that define the position of a point on the sphere, and can be used to describe the properties of the sphere at that point.

4. What are some applications of linear combinations of spherical harmonics?

Linear combinations of spherical harmonics are used in many different fields, including physics, chemistry, and computer graphics. They are particularly useful for solving problems that involve spherical symmetry, such as predicting the behavior of particles in a spherical potential well or creating realistic lighting effects in computer-generated images.

5. How are linear combinations of spherical harmonics calculated?

Calculating linear combinations of spherical harmonics involves finding the appropriate coefficients for each individual spherical harmonic and combining them according to the desired mathematical expression. This can be done using various techniques, such as numerical integration or solving systems of equations.

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