nalgebra/src/linalg/decomposition.rs
2021-02-28 17:52:14 +01:00

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use crate::storage::Storage;
use crate::{
Allocator, Bidiagonal, Cholesky, ColPivQR, ComplexField, DefaultAllocator, Dim, DimDiff,
DimMin, DimMinimum, DimSub, FullPivLU, Hessenberg, Matrix, RealField, Schur, SymmetricEigen,
SymmetricTridiagonal, LU, QR, SVD, U1, UDU,
};
/// # Rectangular matrix decomposition
///
/// This section contains the methods for computing some common decompositions of rectangular
/// matrices with real or complex components. The following are currently supported:
///
/// | Decomposition | Factors | Details |
/// | -------------------------|---------------------|--------------|
/// | QR | `Q * R` | `Q` is an unitary matrix, and `R` is upper-triangular. |
/// | QR with column pivoting | `Q * R * P⁻¹` | `Q` is an unitary matrix, and `R` is upper-triangular. `P` is a permutation matrix. |
/// | LU with partial pivoting | `P⁻¹ * L * U` | `L` is lower-triangular with a diagonal filled with `1` and `U` is upper-triangular. `P` is a permutation matrix. |
/// | LU with full pivoting | `P⁻¹ * L * U * Q⁻¹` | `L` is lower-triangular with a diagonal filled with `1` and `U` is upper-triangular. `P` and `Q` are permutation matrices. |
/// | SVD | `U * Σ * Vᵀ` | `U` and `V` are two orthogonal matrices and `Σ` is a diagonal matrix containing the singular values. |
impl<N: ComplexField, R: Dim, C: Dim, S: Storage<N, R, C>> Matrix<N, R, C, S> {
/// Computes the bidiagonalization using householder reflections.
pub fn bidiagonalize(self) -> Bidiagonal<N, R, C>
where
R: DimMin<C>,
DimMinimum<R, C>: DimSub<U1>,
DefaultAllocator: Allocator<N, R, C>
+ Allocator<N, C>
+ Allocator<N, R>
+ Allocator<N, DimMinimum<R, C>>
+ Allocator<N, DimDiff<DimMinimum<R, C>, U1>>,
{
Bidiagonal::new(self.into_owned())
}
/// Computes the LU decomposition with full pivoting of `matrix`.
///
/// This effectively computes `P, L, U, Q` such that `P * matrix * Q = LU`.
pub fn full_piv_lu(self) -> FullPivLU<N, R, C>
where
R: DimMin<C>,
DefaultAllocator: Allocator<N, R, C> + Allocator<(usize, usize), DimMinimum<R, C>>,
{
FullPivLU::new(self.into_owned())
}
/// Computes the LU decomposition with partial (row) pivoting of `matrix`.
pub fn lu(self) -> LU<N, R, C>
where
R: DimMin<C>,
DefaultAllocator: Allocator<N, R, C> + Allocator<(usize, usize), DimMinimum<R, C>>,
{
LU::new(self.into_owned())
}
/// Computes the QR decomposition of this matrix.
pub fn qr(self) -> QR<N, R, C>
where
R: DimMin<C>,
DefaultAllocator: Allocator<N, R, C> + Allocator<N, R> + Allocator<N, DimMinimum<R, C>>,
{
QR::new(self.into_owned())
}
/// Computes the QR decomposition (with column pivoting) of this matrix.
pub fn col_piv_qr(self) -> ColPivQR<N, R, C>
where
R: DimMin<C>,
DefaultAllocator: Allocator<N, R, C>
+ Allocator<N, R>
+ Allocator<N, DimMinimum<R, C>>
+ Allocator<(usize, usize), DimMinimum<R, C>>,
{
ColPivQR::new(self.into_owned())
}
/// Computes the Singular Value Decomposition using implicit shift.
pub fn svd(self, compute_u: bool, compute_v: bool) -> SVD<N, R, C>
where
R: DimMin<C>,
DimMinimum<R, C>: DimSub<U1>, // for Bidiagonal.
DefaultAllocator: Allocator<N, R, C>
+ Allocator<N, C>
+ Allocator<N, R>
+ Allocator<N, DimDiff<DimMinimum<R, C>, U1>>
+ Allocator<N, DimMinimum<R, C>, C>
+ Allocator<N, R, DimMinimum<R, C>>
+ Allocator<N, DimMinimum<R, C>>
+ Allocator<N::RealField, DimMinimum<R, C>>
+ Allocator<N::RealField, DimDiff<DimMinimum<R, C>, U1>>,
{
SVD::new(self.into_owned(), compute_u, compute_v)
}
/// Attempts to compute the Singular Value Decomposition of `matrix` using implicit shift.
///
/// # Arguments
///
/// * `compute_u` set this to `true` to enable the computation of left-singular vectors.
/// * `compute_v` set this to `true` to enable the computation of right-singular vectors.
/// * `eps` tolerance used to determine when a value converged to 0.
/// * `max_niter` maximum total number of iterations performed by the algorithm. If this
/// number of iteration is exceeded, `None` is returned. If `niter == 0`, then the algorithm
/// continues indefinitely until convergence.
pub fn try_svd(
self,
compute_u: bool,
compute_v: bool,
eps: N::RealField,
max_niter: usize,
) -> Option<SVD<N, R, C>>
where
R: DimMin<C>,
DimMinimum<R, C>: DimSub<U1>, // for Bidiagonal.
DefaultAllocator: Allocator<N, R, C>
+ Allocator<N, C>
+ Allocator<N, R>
+ Allocator<N, DimDiff<DimMinimum<R, C>, U1>>
+ Allocator<N, DimMinimum<R, C>, C>
+ Allocator<N, R, DimMinimum<R, C>>
+ Allocator<N, DimMinimum<R, C>>
+ Allocator<N::RealField, DimMinimum<R, C>>
+ Allocator<N::RealField, DimDiff<DimMinimum<R, C>, U1>>,
{
SVD::try_new(self.into_owned(), compute_u, compute_v, eps, max_niter)
}
}
/// # Square matrix decomposition
///
/// This section contains the methods for computing some common decompositions of square
/// matrices with real or complex components. The following are currently supported:
///
/// | Decomposition | Factors | Details |
/// | -------------------------|---------------------------|--------------|
/// | Hessenberg | `Q * H * Qᵀ` | `Q` is a unitary matrix and `H` an upper-Hessenberg matrix. |
/// | Cholesky | `L * Lᵀ` | `L` is a lower-triangular matrix. |
/// | UDU | `U * D * Uᵀ` | `U` is a upper-triangular matrix, and `D` a diagonal matrix. |
/// | Schur decomposition | `Q * T * Qᵀ` | `Q` is an unitary matrix and `T` a quasi-upper-triangular matrix. |
/// | Symmetric eigendecomposition | `Q ~ Λ ~ Qᵀ` | `Q` is an unitary matrix, and `Λ` is a real diagonal matrix. |
/// | Symmetric tridiagonalization | `Q ~ T ~ Qᵀ` | `Q` is an unitary matrix, and `T` is a tridiagonal matrix. |
impl<N: ComplexField, D: Dim, S: Storage<N, D, D>> Matrix<N, D, D, S> {
/// Attempts to compute the Cholesky decomposition of this matrix.
///
/// Returns `None` if the input matrix is not definite-positive. The input matrix is assumed
/// to be symmetric and only the lower-triangular part is read.
pub fn cholesky(self) -> Option<Cholesky<N, D>>
where
DefaultAllocator: Allocator<N, D, D>,
{
Cholesky::new(self.into_owned())
}
/// Attempts to compute the UDU decomposition of this matrix.
///
/// The input matrix `self` is assumed to be symmetric and this decomposition will only read
/// the upper-triangular part of `self`.
pub fn udu(self) -> Option<UDU<N, D>>
where
N: RealField,
DefaultAllocator: Allocator<N, D> + Allocator<N, D, D>,
{
UDU::new(self.into_owned())
}
/// Computes the Hessenberg decomposition of this matrix using householder reflections.
pub fn hessenberg(self) -> Hessenberg<N, D>
where
D: DimSub<U1>,
DefaultAllocator: Allocator<N, D, D> + Allocator<N, D> + Allocator<N, DimDiff<D, U1>>,
{
Hessenberg::new(self.into_owned())
}
/// Computes the Schur decomposition of a square matrix.
pub fn schur(self) -> Schur<N, D>
where
D: DimSub<U1>, // For Hessenberg.
DefaultAllocator: Allocator<N, D, DimDiff<D, U1>>
+ Allocator<N, DimDiff<D, U1>>
+ Allocator<N, D, D>
+ Allocator<N, D>,
{
Schur::new(self.into_owned())
}
/// Attempts to compute the Schur decomposition of a square matrix.
///
/// If only eigenvalues are needed, it is more efficient to call the matrix method
/// `.eigenvalues()` instead.
///
/// # Arguments
///
/// * `eps` tolerance used to determine when a value converged to 0.
/// * `max_niter` maximum total number of iterations performed by the algorithm. If this
/// number of iteration is exceeded, `None` is returned. If `niter == 0`, then the algorithm
/// continues indefinitely until convergence.
pub fn try_schur(self, eps: N::RealField, max_niter: usize) -> Option<Schur<N, D>>
where
D: DimSub<U1>, // For Hessenberg.
DefaultAllocator: Allocator<N, D, DimDiff<D, U1>>
+ Allocator<N, DimDiff<D, U1>>
+ Allocator<N, D, D>
+ Allocator<N, D>,
{
Schur::try_new(self.into_owned(), eps, max_niter)
}
/// Computes the eigendecomposition of this symmetric matrix.
///
/// Only the lower-triangular part (including the diagonal) of `m` is read.
pub fn symmetric_eigen(self) -> SymmetricEigen<N, D>
where
D: DimSub<U1>,
DefaultAllocator: Allocator<N, D, D>
+ Allocator<N, DimDiff<D, U1>>
+ Allocator<N::RealField, D>
+ Allocator<N::RealField, DimDiff<D, U1>>,
{
SymmetricEigen::new(self.into_owned())
}
/// Computes the eigendecomposition of the given symmetric matrix with user-specified
/// convergence parameters.
///
/// Only the lower-triangular part (including the diagonal) of `m` is read.
///
/// # Arguments
///
/// * `eps` tolerance used to determine when a value converged to 0.
/// * `max_niter` maximum total number of iterations performed by the algorithm. If this
/// number of iteration is exceeded, `None` is returned. If `niter == 0`, then the algorithm
/// continues indefinitely until convergence.
pub fn try_symmetric_eigen(
self,
eps: N::RealField,
max_niter: usize,
) -> Option<SymmetricEigen<N, D>>
where
D: DimSub<U1>,
DefaultAllocator: Allocator<N, D, D>
+ Allocator<N, DimDiff<D, U1>>
+ Allocator<N::RealField, D>
+ Allocator<N::RealField, DimDiff<D, U1>>,
{
SymmetricEigen::try_new(self.into_owned(), eps, max_niter)
}
/// Computes the tridiagonalization of this symmetric matrix.
///
/// Only the lower-triangular part (including the diagonal) of `m` is read.
pub fn symmetric_tridiagonalize(self) -> SymmetricTridiagonal<N, D>
where
D: DimSub<U1>,
DefaultAllocator: Allocator<N, D, D> + Allocator<N, DimDiff<D, U1>>,
{
SymmetricTridiagonal::new(self.into_owned())
}
}