mathru 0.16.2

Fundamental algorithms for scientific computing in Rust
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100

use crate::algebra::linear::matrix::Transpose;
use crate::algebra::{
    abstr::{Field, Scalar},
    linear::matrix::General,
};

impl<T> General<T> {
    pub fn gcd(mut m: usize, mut n: usize) -> usize {
        while m != 0 {
            let old_m: usize = m;
            m = n % m;
            n = old_m;
        }
        n
    }

    fn gather(&self, i: usize, j: usize, b: usize) -> usize {
        (i + (j / b)) % self.m
    }

    fn gather_sa(&self, i: usize, j: usize, a: usize) -> usize {
        (j + i * self.n - i / a) % self.m
    }

    fn scatter_da(&self, i: usize, j: usize, b: usize) -> usize {
        (((i + j / b) % self.m) + j * self.m) % self.n
    }
}

impl<T> Transpose for General<T>
where
    T: Field + Scalar,
{
    type Output = General<T>;

    /// Transpose a matrix without allocating memory for the transposed matrix
    ///
    /// catanzaro.name/papers/PPoPP-2014.pdf
    ///
    /// # Example
    ///
    /// ```
    /// use mathru::algebra::linear::matrix::{Transpose, General};
    /// use mathru::assert_relative_eq;
    ///
    /// let mut uut: General<f64> = General::new(4, 2, vec![1.0, 0.0, 3.0, 0.0, 1.0, -7.0, 0.5, 0.25]);
    /// uut = uut.transpose();
    ///
    /// let refer: General<f64> = General::new(2, 4, vec![1.0, 1.0, 0.0, -7.0, 3.0, 0.5, 0.0, 0.25]);
    /// assert_relative_eq!(refer, uut);
    /// ```
    fn transpose(mut self) -> General<T> {
        let gcdiv: usize = General::<T>::gcd(self.m, self.n);

        std::mem::swap(&mut self.m, &mut self.n);

        let a: usize = self.m / gcdiv;
        let b: usize = self.n / gcdiv;

        let bigger: usize = self.m.max(self.n);

        let mut temp: Vec<T> = Vec::with_capacity(bigger);
        //Bad
        unsafe { temp.set_len(bigger) };

        if gcdiv > 1 {
            for j in 0..self.n {
                for i in 0..self.m {
                    temp[i] = self[[self.gather(i, j, b), j]]
                }

                for i in 0..self.m {
                    self[[i, j]] = temp[i];
                }
            }
        }

        for i in 0..self.m {
            for j in 0..self.n {
                temp[self.scatter_da(i, j, b)] = self[[i, j]];
            }

            for j in 0..self.n {
                self[[i, j]] = temp[j];
            }
        }

        for j in 0..self.n {
            for i in 0..self.m {
                temp[i] = self[[self.gather_sa(i, j, a), j]];
            }

            for i in 0..self.m {
                self[[i, j]] = temp[i];
            }
        }

        self
    }
}