1use ark_ff::PrimeField;
  2pub use ark_relations::r1cs::Matrix as R1CSMatrix;
  3use ark_std::cfg_iter;
  4use rayon::iter::{IndexedParallelIterator, IntoParallelRefIterator, ParallelIterator};
  5
  6use crate::Error;
  7
  8#[derive(Clone, Debug, Eq, PartialEq)]
  9pub struct SparseMatrix<F: PrimeField> {
 10    pub n_rows: usize,
 11    pub n_cols: usize,
 12    /// coeffs = R1CSMatrix = Vec<Vec<(F, usize)>>, which contains each row and the F is the value
 13    /// of the coefficient and the usize indicates the column position
 14    pub coeffs: R1CSMatrix<F>,
 15}
 16
 17impl<F: PrimeField> SparseMatrix<F> {
 18    pub fn to_dense(&self) -> Vec<Vec<F>> {
 19        let mut r: Vec<Vec<F>> = vec![vec![F::zero(); self.n_cols]; self.n_rows];
 20        for (row_i, row) in self.coeffs.iter().enumerate() {
 21            for &(value, col_i) in row.iter() {
 22                r[row_i][col_i] = value;
 23            }
 24        }
 25        r
 26    }
 27}
 28
 29pub fn dense_matrix_to_sparse<F: PrimeField>(m: Vec<Vec<F>>) -> SparseMatrix<F> {
 30    let mut r = SparseMatrix::<F> {
 31        n_rows: m.len(),
 32        n_cols: m[0].len(),
 33        coeffs: Vec::new(),
 34    };
 35    for m_row in m.iter() {
 36        let mut row: Vec<(F, usize)> = Vec::new();
 37        for (col_i, value) in m_row.iter().enumerate() {
 38            if !value.is_zero() {
 39                row.push((*value, col_i));
 40            }
 41        }
 42        r.coeffs.push(row);
 43    }
 44    r
 45}
 46
 47pub fn vec_add<F: PrimeField>(a: &[F], b: &[F]) -> Result<Vec<F>, Error> {
 48    if a.len() != b.len() {
 49        return Err(Error::NotSameLength(a.len(), b.len()));
 50    }
 51    Ok(a.iter().zip(b.iter()).map(|(x, y)| *x + y).collect())
 52}
 53
 54pub fn vec_sub<F: PrimeField>(a: &[F], b: &[F]) -> Result<Vec<F>, Error> {
 55    if a.len() != b.len() {
 56        return Err(Error::NotSameLength(a.len(), b.len()));
 57    }
 58    Ok(a.iter().zip(b.iter()).map(|(x, y)| *x - y).collect())
 59}
 60
 61pub fn vec_scalar_mul<F: PrimeField>(vec: &[F], c: &F) -> Vec<F> {
 62    vec.iter().map(|a| *a * c).collect()
 63}
 64
 65pub fn is_zero_vec<F: PrimeField>(vec: &[F]) -> bool {
 66    vec.iter().all(|a| a.is_zero())
 67}
 68
 69pub fn mat_vec_mul<F: PrimeField>(M: &Vec<Vec<F>>, z: &[F]) -> Result<Vec<F>, Error> {
 70    if M.is_empty() {
 71        return Err(Error::Empty);
 72    }
 73    if M[0].len() != z.len() {
 74        return Err(Error::NotSameLength(M[0].len(), z.len()));
 75    }
 76
 77    let mut r: Vec<F> = vec![F::zero(); M.len()];
 78    for (i, M_i) in M.iter().enumerate() {
 79        for (j, M_ij) in M_i.iter().enumerate() {
 80            r[i] += *M_ij * z[j];
 81        }
 82    }
 83    Ok(r)
 84}
 85
 86pub fn mat_vec_mul_sparse<F: PrimeField>(M: &SparseMatrix<F>, z: &[F]) -> Result<Vec<F>, Error> {
 87    if M.n_cols != z.len() {
 88        return Err(Error::NotSameLength(M.n_cols, z.len()));
 89    }
 90    let mut res = vec![F::zero(); M.n_rows];
 91    for (row_i, row) in M.coeffs.iter().enumerate() {
 92        for &(value, col_i) in row.iter() {
 93            res[row_i] += value * z[col_i];
 94        }
 95    }
 96    Ok(res)
 97}
 98
 99pub fn hadamard<F: PrimeField>(a: &[F], b: &[F]) -> Result<Vec<F>, Error> {
100    if a.len() != b.len() {
101        return Err(Error::NotSameLength(a.len(), b.len()));
102    }
103    Ok(cfg_iter!(a).zip(b).map(|(a, b)| *a * b).collect())
104}
105
106#[cfg(test)]
107pub mod tests {
108    use super::*;
109    use ark_pallas::Fr;
110
111    pub fn to_F_matrix<F: PrimeField>(M: Vec<Vec<usize>>) -> SparseMatrix<F> {
112        dense_matrix_to_sparse(to_F_dense_matrix(M))
113    }
114    pub fn to_F_dense_matrix<F: PrimeField>(M: Vec<Vec<usize>>) -> Vec<Vec<F>> {
115        M.iter()
116            .map(|m| m.iter().map(|r| F::from(*r as u64)).collect())
117            .collect()
118    }
119    pub fn to_F_vec<F: PrimeField>(z: Vec<usize>) -> Vec<F> {
120        z.iter().map(|c| F::from(*c as u64)).collect()
121    }
122
123    #[test]
124    fn test_dense_sparse_conversions() {
125        let A = to_F_dense_matrix::<Fr>(vec![
126            vec![0, 1, 0, 0, 0, 0],
127            vec![0, 0, 0, 1, 0, 0],
128            vec![0, 1, 0, 0, 1, 0],
129            vec![5, 0, 0, 0, 0, 1],
130        ]);
131        let A_sparse = dense_matrix_to_sparse(A.clone());
132        assert_eq!(A_sparse.to_dense(), A);
133    }
134
135    // test mat_vec_mul & mat_vec_mul_sparse
136    #[test]
137    fn test_mat_vec_mul() {
138        let A = to_F_matrix::<Fr>(vec![
139            vec![0, 1, 0, 0, 0, 0],
140            vec![0, 0, 0, 1, 0, 0],
141            vec![0, 1, 0, 0, 1, 0],
142            vec![5, 0, 0, 0, 0, 1],
143        ])
144        .to_dense();
145        let z = to_F_vec(vec![1, 3, 35, 9, 27, 30]);
146        assert_eq!(mat_vec_mul(&A, &z).unwrap(), to_F_vec(vec![3, 9, 30, 35]));
147        assert_eq!(
148            mat_vec_mul_sparse(&dense_matrix_to_sparse(A), &z).unwrap(),
149            to_F_vec(vec![3, 9, 30, 35])
150        );
151
152        let A = to_F_matrix::<Fr>(vec![vec![2, 3, 4, 5], vec![4, 8, 12, 14], vec![9, 8, 7, 6]]);
153        let v = to_F_vec(vec![19, 55, 50, 3]);
154
155        assert_eq!(
156            mat_vec_mul(&A.to_dense(), &v).unwrap(),
157            to_F_vec(vec![418, 1158, 979])
158        );
159        assert_eq!(
160            mat_vec_mul_sparse(&A, &v).unwrap(),
161            to_F_vec(vec![418, 1158, 979])
162        );
163    }
164
165    #[test]
166    fn test_hadamard_product() {
167        let a = to_F_vec::<Fr>(vec![1, 2, 3, 4, 5, 6]);
168        let b = to_F_vec(vec![7, 8, 9, 10, 11, 12]);
169        assert_eq!(
170            hadamard(&a, &b).unwrap(),
171            to_F_vec(vec![7, 16, 27, 40, 55, 72])
172        );
173    }
174
175    #[test]
176    fn test_vec_add() {
177        let a: Vec<Fr> = to_F_vec::<Fr>(vec![1, 2, 3, 4, 5, 6]);
178        let b: Vec<Fr> = to_F_vec(vec![7, 8, 9, 10, 11, 12]);
179        assert_eq!(
180            vec_add(&a, &b).unwrap(),
181            to_F_vec(vec![8, 10, 12, 14, 16, 18])
182        );
183    }
184}