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use ndarray::{Ix2, Array, LinalgScalar};
use std::fmt::Debug;
use num_traits::float::Float;
use lapack::c::Layout;
use matrix::Matrix;
use error::{LinalgError, NotSquareError};
use qr::ImplQR;
use svd::ImplSVD;
use norm::ImplNorm;
use solve::ImplSolve;
pub trait SquareMatrix: Matrix {
fn inv(self) -> Result<Self, LinalgError>;
fn trace(&self) -> Result<Self::Scalar, LinalgError>;
fn check_square(&self) -> Result<(), NotSquareError> {
let (rows, cols) = self.size();
if rows == cols {
Ok(())
} else {
Err(NotSquareError {
rows: rows,
cols: cols,
})
}
}
}
impl<A> SquareMatrix for Array<A, Ix2>
where A: ImplQR + ImplNorm + ImplSVD + ImplSolve + LinalgScalar + Float + Debug
{
fn inv(self) -> Result<Self, LinalgError> {
self.check_square()?;
let (n, _) = self.size();
let layout = self.layout()?;
let (ipiv, a) = ImplSolve::lu(layout, n, n, self.into_raw_vec())?;
let a = ImplSolve::inv(layout, n, a, &ipiv)?;
let m = Array::from_vec(a).into_shape((n, n)).unwrap();
match layout {
Layout::RowMajor => Ok(m),
Layout::ColumnMajor => Ok(m.reversed_axes()),
}
}
fn trace(&self) -> Result<Self::Scalar, LinalgError> {
self.check_square()?;
let (n, _) = self.size();
Ok((0..n).fold(A::zero(), |sum, i| sum + self[(i, i)]))
}
}