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first version of rank one update

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Nestor Demeure 2019-11-02 14:59:07 +01:00
parent ead2360f8e
commit 2beb09dab2
1 changed files with 44 additions and 14 deletions
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58
src/linalg/cholesky.rs
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@ -6,28 +6,25 @@ use alga::general::ComplexField;
use crate::allocator::Allocator;
use crate::base::{DefaultAllocator, Matrix, MatrixMN, MatrixN, SquareMatrix};
use crate::constraint::{SameNumberOfRows, ShapeConstraint};
use crate::dimension::{Dim, DimSub, Dynamic};
use crate::dimension::{Dim, DimSub, Dynamic, U1};
use crate::storage::{Storage, StorageMut};
/// The Cholesky decomposition of a symmetric-definite-positive matrix.
#[cfg_attr(feature = "serde-serialize", derive(Serialize, Deserialize))]
#[cfg_attr(
feature = "serde-serialize",
serde(bound(
serialize = "DefaultAllocator: Allocator<N, D>,
MatrixN<N, D>: Serialize"
))
serde(bound(serialize = "DefaultAllocator: Allocator<N, D>,
MatrixN<N, D>: Serialize"))
)]
#[cfg_attr(
feature = "serde-serialize",
serde(bound(
deserialize = "DefaultAllocator: Allocator<N, D>,
MatrixN<N, D>: Deserialize<'de>"
))
serde(bound(deserialize = "DefaultAllocator: Allocator<N, D>,
MatrixN<N, D>: Deserialize<'de>"))
)]
#[derive(Clone, Debug)]
pub struct Cholesky<N: ComplexField, D: Dim>
where DefaultAllocator: Allocator<N, D, D>
where
DefaultAllocator: Allocator<N, D, D>,
{
chol: MatrixN<N, D>,
}
@ -36,10 +33,12 @@ impl<N: ComplexField, D: Dim> Copy for Cholesky<N, D>
where
DefaultAllocator: Allocator<N, D, D>,
MatrixN<N, D>: Copy,
{}
{
}
impl<N: ComplexField, D: DimSub<Dynamic>> Cholesky<N, D>
where DefaultAllocator: Allocator<N, D, D>
where
DefaultAllocator: Allocator<N, D, D>,
{
/// Attempts to compute the Cholesky decomposition of `matrix`.
///
@ -129,7 +128,7 @@ where DefaultAllocator: Allocator<N, D, D>
/// `x` the unknown.
pub fn solve<R2: Dim, C2: Dim, S2>(&self, b: &Matrix<N, R2, C2, S2>) -> MatrixMN<N, R2, C2>
where
S2: StorageMut<N, R2, C2>,
S2: Storage<N, R2, C2>,
DefaultAllocator: Allocator<N, R2, C2>,
ShapeConstraint: SameNumberOfRows<R2, D>,
{
@ -146,10 +145,41 @@ where DefaultAllocator: Allocator<N, D, D>
self.solve_mut(&mut res);
res
}
/// Performs a rank one update of the current decomposition.
/// If `M = L * L^T` before the rank one update, then after it we have `L*L^T = M + sigma * v*v^T` where v must be a vector of same dimension.
/// TODO rewrite comment (current version is taken verbatim from eigen)
/// TODO insures that code is correct for complex numbers, eigen uses abs2 and conj
/// https://eigen.tuxfamily.org/dox/LLT_8h_source.html
pub fn rank_one_update<R2: Dim, C2: Dim, S2>(&mut self, x: &Matrix<N, R2, U1, S2>, sigma: N)
where
S2: Storage<N, R2, U1>,
DefaultAllocator: Allocator<N, R2, U1>,
ShapeConstraint: SameNumberOfRows<R2, D>,
{
let n = x.nrows();
let mut temp = x.clone_owned();
for k in 0..n {
let lkk = self.chol[(k, k)]; // TODO unsafe { *matrix.get_unchecked((j, j)) }
let xk = temp[k];
let r = (lkk * lkk + sigma * xk * xk).sqrt();
let c = r / lkk;
let s = xk / lkk;
self.chol[(k, k)] = r;
// Update the terms of L
if k < n {
for k2 in (k + 1)..n {
self.chol[(k2, k)] = (self.chol[(k2, k)] + sigma * s * temp[k2]) / c;
temp[k2] = c * temp[k2] - s * self.chol[(k2, k)];
}
}
}
}
}
impl<N: ComplexField, D: DimSub<Dynamic>, S: Storage<N, D, D>> SquareMatrix<N, D, S>
where DefaultAllocator: Allocator<N, D, D>
where
DefaultAllocator: Allocator<N, D, D>,
{
/// Attempts to compute the Cholesky decomposition of this matrix.
///