Added test for linalg::solve. Fix bug in fitter (wrong argument order)

src/linalg.rs

@@ -29,7 +29,7 @@ pub fn solve(mut a: Array2<f64>, mut b: Array2<f64>) -> Array2<f64> {
     let mut ipiv = vec![0; n as usize];
 
     let (a_slice, layout) = as_slice_with_layout_mut(&mut a).expect("Matrix `a` not contiguous.");
-    let (b_slice, _) = as_slice_with_layout_mut(&mut b).expect("Matrix `a` not contiguous.");
+    let (b_slice, _) = as_slice_with_layout_mut(&mut b).expect("Matrix `b` not contiguous.");
 
     unsafe {
         info = lapacke::dgesv(layout, n, nrhs, a_slice, lda, &mut ipiv, b_slice, ldb);
@@ -39,3 +39,27 @@ pub fn solve(mut a: Array2<f64>, mut b: Array2<f64>) -> Array2<f64> {
 
     b
 }
+
+#[cfg(test)]
+mod tests {
+    use approx::assert_relative_eq;
+
+    use super::*;
+
+    #[test]
+    fn test_solve() {
+        let a = array![[2.0, 0.0], [0.0, 6.0]];
+        let b = array![[1.9645574, 0.56996938], [-0.56996938, 3.91924033]];
+
+        let e = array![[0.9822787, 0.28498469], [-0.0949949, 0.65320672]];
+
+        assert_relative_eq!(solve(a, b), e, max_relative = 0.0000001);
+
+        let a = array![[1.22650294, 0.67685001], [0.67685001, 5.34978493]];
+        let b = array![[1.00213885, 1.47494613], [-0.03356356, 2.14214437]];
+
+        let e = array![[0.88212208, 1.0552697], [-0.11787911, 0.26690514]];
+
+        assert_relative_eq!(solve(a, b), e, max_relative = 0.0000001);
+    }
+}