Some test fixes and adding initial simple version of matrix data struct

src/matrix.rs

@@ -0,0 +1,135 @@
+use std::fmt;
+use std::{
+    fmt::Display,
+    ops::{Add, Div, Mul, Sub},
+};
+
+/// Numeric trait as an alias to make the generics a little bit cleaner
+pub trait Numeric:
+    Add<Output = Self>
+    + Sub<Output = Self>
+    + Mul<Output = Self>
+    + Div<Output = Self>
+    + Sized
+    + Clone
+    + Display
+{
+}
+
+/// Blanket implementation for numeric types
+impl<T> Numeric for T where
+    T: Add<Output = Self>
+        + Sub<Output = Self>
+        + Mul<Output = Self>
+        + Div<Output = Self>
+        + Sized
+        + Clone
+        + Display
+{
+}
+
+// Basic Error handling for Matrix operations
+#[derive(Debug)]
+pub enum MatrixError {
+    IndexError(usize, usize, usize, usize),
+}
+
+impl fmt::Display for MatrixError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            MatrixError::IndexError(i, j, m, n) => write!(
+                f,
+                "Error accessing index [{i},{j}] for matrix with dimensions [{}, {}]",
+                m, n
+            ),
+        }
+    }
+}
+
+fn make_index_error<T>(i: usize, j: usize, m: &Matrix<T>) -> MatrixError {
+    MatrixError::IndexError(i, j, m.m, m.n)
+}
+
+pub struct Matrix<T> {
+    data: Vec<T>,
+    m: usize,
+    n: usize,
+}
+
+impl<T: Numeric> Matrix<T> {
+    pub fn new(m: usize, n: usize, init_val: T) -> Self {
+        let data = vec![init_val; n * m];
+        Matrix { data, m, n }
+    }
+
+    fn index(&self, i: usize, j: usize) -> usize {
+        i * self.n + j
+    }
+    pub fn get(&self, i: usize, j: usize) -> Result<&T, MatrixError> {
+        self.data
+            .get(self.index(i, j))
+            .ok_or(make_index_error(i, j, &self))
+    }
+
+    pub fn set(&mut self, i: usize, j: usize, x: T) {
+        let index = self.index(i, j);
+        self.data[index] = x;
+    }
+}
+
+impl<T: Numeric> Display for Matrix<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let msg = (0..self.m)
+            .flat_map(|i| {
+                let mut parts = vec!["|".to_string()];
+                parts.extend((0..self.n).map(|j| -> String {
+                    if let Ok(val) = self.get(i, j) {
+                        format!("{}", val)
+                    } else {
+                        "err".to_string()
+                    }
+                }));
+                parts.push("|\n".to_string());
+                parts
+            })
+            .collect::<Vec<String>>()
+            .join(" ");
+        write!(f, "\n{msg}")
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::{assert_delta, matrix::Matrix};
+    fn gen_test_matrix() -> Matrix<f64> {
+        let mut m = Matrix::new(3, 4, 0.0);
+        m.set(0, 0, 1.0);
+        m.set(1, 1, 1.0);
+        m.set(2, 2, 1.0);
+        m.set(0, 3, 2.0);
+        m.set(1, 3, 2.0);
+        m.set(2, 3, 2.0);
+        m
+    }
+
+    #[test]
+    fn test_matrix_basics() {
+        let m = gen_test_matrix();
+
+        // Validate that the matrix type returns the right values
+        assert_delta!(m.get(0, 0).unwrap(), 1.0, 1e-12);
+        assert_delta!(m.get(1, 1).unwrap(), 1.0, 1e-12);
+        assert_delta!(m.get(2, 2).unwrap(), 1.0, 1e-12);
+        assert_delta!(m.get(0, 3).unwrap(), 2.0, 1e-12);
+        assert_delta!(m.get(1, 3).unwrap(), 2.0, 1e-12);
+        assert_delta!(m.get(2, 3).unwrap(), 2.0, 1e-12);
+
+        // Validate that the memory is laid out as expected
+        assert_delta!(m.data[0], 1.0, 1e-12);
+        assert_delta!(m.data[3], 2.0, 1e-12);
+        assert_delta!(m.data[5], 1.0, 1e-12);
+        assert_delta!(m.data[7], 2.0, 1e-12);
+        assert_delta!(m.data[10], 1.0, 1e-12);
+        assert_delta!(m.data[11], 2.0, 1e-12);
+    }
+}