rust-linear-algebra 0.1.2

A linear algebra library for Rust
Documentation 
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use super::Matrix;
use crate::num::MinusOne;
use crate::num::One;
use std::fmt::Debug;
use std::ops::{Add, Div, Mul, Sub, SubAssign};

impl<K> Matrix<K>
where
    K: Debug
        + Copy
        + One
        + MinusOne
        + Default
        + PartialEq
        + Add<Output = K>
        + Sub<Output = K>
        + SubAssign<K>
        + Mul<Output = K>
        + Div<Output = K>,
{
    fn find_pivot(&self, start_row: usize, col: usize) -> Option<usize> {
        for row in start_row..self.rows() {
            if self.elements[row][col] != K::default() {
                return Some(row);
            }
        }
        None
    }

    fn div_row(&mut self, row: usize, scalar: K) {
        self.elements[row]
            .iter_mut()
            .for_each(|element| *element = *element / scalar);
    }

    pub(crate) fn gaussian_elimination(
        &self,
        mut det: Option<&mut K>,
        mut identity_mat: Option<&mut Matrix<K>>,
    ) -> Matrix<K> {
        if self.elements.is_empty() || self.elements[0].is_empty() {
            return self.clone();
        }

        let mut result = self.clone();
        let mut pivot_row = 0;
        let mut sign = K::one();

        for col in 0..result.cols() {
            if let Some(pivot) = result.find_pivot(pivot_row, col) {
                if pivot != pivot_row {
                    result.elements.swap(pivot_row, pivot);

                    if let Some(ref mut identity) = identity_mat {
                        identity.elements.swap(pivot_row, pivot);
                    }

                    sign = sign * K::minus_one();
                }

                let pivot_value = result.elements[pivot_row][col];

                if let Some(ref mut determinant) = det {
                    **determinant = **determinant * pivot_value;
                }

                result.div_row(pivot_row, pivot_value);

                if let Some(ref mut identity) = identity_mat {
                    identity.div_row(pivot_row, pivot_value);
                }

                for row in 0..result.rows() {
                    if row == pivot_row {
                        continue;
                    }

                    let factor = result.elements[row][col];
                    if factor == K::default() {
                        continue;
                    }

                    for column in col..result.cols() {
                        let pivot_value = result.elements[pivot_row][column];
                        result.elements[row][column] -= factor * pivot_value;
                    }

                    if let Some(ref mut identity) = identity_mat {
                        for column in 0..identity.cols() {
                            let pivot_identity_value = identity.elements[pivot_row][column];
                            identity.elements[row][column] -= factor * pivot_identity_value;
                        }
                    }
                }

                pivot_row += 1;
            } else {
                if let Some(ref mut determinant) = det {
                    **determinant = K::default();
                }
            }
        }

        if let Some(ref mut determinant) = det {
            **determinant = **determinant * sign;
        }

        result
    }
}