A hermitian matrix @math{A} can be factorized by similarity transformations into the form,

where @math{U} is an unitary matrix and @math{T} is a real symmetric tridiagonal matrix.

__Function:__int**gsl_linalg_hermtd_decomp***(gsl_matrix_complex **`A`, gsl_vector_complex *`tau`)-
This function factorizes the hermitian matrix
`A`into the symmetric tridiagonal decomposition @math{U T U^T}. On output the real parts of the diagonal and subdiagonal part of the input matrix`A`contain the tridiagonal matrix @math{T}. The remaining lower triangular part of the input matrix contains the Householder vectors which, together with the Householder coefficients`tau`, encode the orthogonal matrix @math{Q}. This storage scheme is the same as used by LAPACK. The upper triangular part of`A`and imaginary parts of the diagonal are not referenced.

__Function:__int**gsl_linalg_hermtd_unpack***(const gsl_matrix_complex **`A`, const gsl_vector_complex *`tau`, gsl_matrix_complex *`Q`, gsl_vector *`d`, gsl_vector *`sd`)-
This function unpacks the encoded tridiagonal decomposition (
`A`,`tau`) obtained from`gsl_linalg_hermtd_decomp`

into the unitary matrix`U`, the real vector of diagonal elements`d`and the real vector of subdiagonal elements`sd`.

__Function:__int**gsl_linalg_hermtd_unpack_dsd***(const gsl_matrix_complex **`A`, gsl_vector *`d`, gsl_vector *`sd`)-
This function unpacks the diagonal and subdiagonal of the encoded
tridiagonal decomposition (
`A`,`tau`) obtained from`gsl_linalg_hermtd_decomp`

into the real vectors`d`and`sd`.

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