Complex Cholesky Decomposition

In summary, the conversation discusses the challenge of finding information on decomposing complex symmetric positive definite matrices and the potential adjustments that may need to be made to the Cholesky decomposition algorithm to accommodate complex numbers. The individual is seeking clarification on the use of complex numbers in the computation and references an algorithm for further understanding.
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magda3227
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I am having trouble finding information about decomposing a complex symmetric positive definite matrix. I was wondering if the cholesky decomposition would change to accommodate complex numbers. I understand that multiplying, dividing, and taking the square root of complex numbers is not the same as with real numbers, but would any additional components need to be added to the algorithm?

I only ask because I am writing a C program and need to implement the Cholesky function. I have written code that works properly for the real decomposition, but when I try to use complex numbers, I am not getting the correct answer.

I did read this, however...
"All the square roots appearing are real. So if one writes a computer programme
implementing the Cholesky factorisation one can be sure that no
complex numbers appear in the course of the computation."

How would this be so? The answer has imaginary parts, not on the diagonals (is that what this means), but elsewhere.
 
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FAQ: Complex Cholesky Decomposition

What is Complex Cholesky Decomposition?

Complex Cholesky Decomposition is a mathematical technique used to decompose a complex Hermitian matrix into a product of a lower triangular matrix and its conjugate transpose. It is similar to the Cholesky Decomposition used for real-valued matrices, but accounts for complex numbers and their conjugates.

What is the purpose of Complex Cholesky Decomposition?

The purpose of Complex Cholesky Decomposition is to simplify the calculation of matrix operations involving complex Hermitian matrices. It is often used in applications such as solving linear systems, computing determinants, and finding eigenvalues and eigenvectors.

How is Complex Cholesky Decomposition performed?

Complex Cholesky Decomposition is performed using a two-step process. First, the matrix is factored into a lower triangular matrix using a modified version of the Cholesky algorithm. Then, the conjugate transpose of the lower triangular matrix is taken to obtain the final result.

What are the advantages of using Complex Cholesky Decomposition?

One advantage of using Complex Cholesky Decomposition is that it reduces the amount of computation required for certain matrix operations involving complex Hermitian matrices. It also provides a more efficient way to store and manipulate these matrices.

Are there any limitations to using Complex Cholesky Decomposition?

One limitation of Complex Cholesky Decomposition is that it can only be applied to complex Hermitian matrices. It also requires the matrix to be positive definite, meaning that all of its eigenvalues are positive. If these conditions are not met, the decomposition cannot be performed.

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