From b3abffb6da502ff691ebac639aea2698a0e21724 Mon Sep 17 00:00:00 2001
From: Gui Castelao <guilherme@castelao.net>
Date: Sat, 3 Aug 2024 15:30:09 -0600
Subject: [PATCH 1/3] test: enthalpy_second_derivatives

Testing error resolved by PR #80.
---
 src/volume.rs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/src/volume.rs b/src/volume.rs
index dfc6c07..104138f 100644
--- a/src/volume.rs
+++ b/src/volume.rs
@@ -2048,6 +2048,28 @@ pub fn enthalpy_first_derivatives(sa: f64, ct: f64, p: f64) -> Result<(f64, f64)
 }
 
 /// Second derivatives of enthalphy  (75-term polynomial approximation)
+///
+/// # Arguments
+///
+/// * `sa`: Absolute Salinity \[ g kg-1 \]
+/// * `ct`: Conservative Temperature (ITS-90) \[ deg C \]
+/// * `p`: sea pressure \[ dbar \] (i.e. absolute pressure - 10.1325 dbar)
+///
+/// # Returns
+///
+/// * `h_sa_sa`
+/// * `h_sa_ct`
+/// * `h_ct_ct`
+///
+/// # Example
+/// ```
+/// use gsw::volume::enthalpy_second_derivatives;
+/// let (sa_sa, sa_ct, ct_ct) = enthalpy_second_derivatives(32.0, 10.0, 100.0).unwrap();
+/// assert!((sa_sa - 0.000991418837118621).abs() <= f64::EPSILON);
+/// assert!((sa_ct - 0.0022484715893934326).abs() <= f64::EPSILON);
+/// assert!((ct_ct - 0.009923131263268556).abs() <= f64::EPSILON);
+/// ```
+///
 pub fn enthalpy_second_derivatives(sa: f64, ct: f64, p: f64) -> Result<(f64, f64, f64)> {
     let s: f64 = non_dimensional_sa(sa)?;
     let tau: f64 = ct / GSW_CTU;

From 3fe208169851f07925e5550d9e2b722960ffc95d Mon Sep 17 00:00:00 2001
From: Gui Castelao <guilherme@castelao.net>
Date: Sat, 3 Aug 2024 15:39:11 -0600
Subject: [PATCH 2/3] style: Wrong identation in code comment

---
 src/volume.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/volume.rs b/src/volume.rs
index 104138f..5f90f5b 100644
--- a/src/volume.rs
+++ b/src/volume.rs
@@ -2169,8 +2169,8 @@ pub fn enthalpy_second_derivatives(sa: f64, ct: f64, p: f64) -> Result<(f64, f64
 /// # Notes:
 ///
 /// - According to the Matlab GSW toolbox, after two iterations of this
-/// modified Newton-Raphson iteration, the error in SA is no larger than
-/// 8e-13 g/kg, which is machine precision for this calculation.
+///   modified Newton-Raphson iteration, the error in SA is no larger than
+///   8e-13 g/kg, which is machine precision for this calculation.
 pub fn sa_from_rho(rho: f64, ct: f64, p: f64) -> Result<f64> {
     let v_lab = 1.0 / rho;
     let v_0 = specvol(0.0, ct, p)?;

From d07b70d6a37d2b6a8535a3e8866c646000f6bf7d Mon Sep 17 00:00:00 2001
From: Gui Castelao <guilherme@castelao.net>
Date: Sat, 3 Aug 2024 16:15:29 -0600
Subject: [PATCH 3/3] test: Verifying a few more values

---
 src/volume.rs | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

diff --git a/src/volume.rs b/src/volume.rs
index 5f90f5b..940ac6f 100644
--- a/src/volume.rs
+++ b/src/volume.rs
@@ -2149,6 +2149,53 @@ pub fn enthalpy_second_derivatives(sa: f64, ct: f64, p: f64) -> Result<(f64, f64
     Ok((h_sa_sa, h_sa_ct, h_ct_ct))
 }
 
+#[cfg(test)]
+mod test_enthaply_second_derivatives {
+    use super::enthalpy_second_derivatives;
+
+    #[test]
+    fn checking_some_values() {
+        let values = [
+            (
+                0.0,
+                0.0,
+                100.0,
+                (
+                    0.004718466663787883,
+                    0.003972891301960524,
+                    0.016214415072100922,
+                ),
+            ),
+            (
+                20.0,
+                20.0,
+                100.0,
+                (
+                    0.0009885322799460053,
+                    0.001775127322073198,
+                    0.00887579007965542,
+                ),
+            ),
+            (
+                30.0,
+                10.0,
+                1000.0,
+                (
+                    0.009759550216647447,
+                    0.02205128100265564,
+                    0.09713432880909768,
+                ),
+            ),
+        ];
+        for (sa, ct, p, ans) in values.iter() {
+            let (h_sa_sa, h_sa_ct, h_ct_ct) = enthalpy_second_derivatives(*sa, *ct, *p).unwrap();
+            assert!((h_sa_sa - ans.0).abs() <= f64::EPSILON);
+            assert!((h_sa_ct - ans.1).abs() <= f64::EPSILON);
+            assert!((h_ct_ct - ans.2).abs() <= f64::EPSILON);
+        }
+    }
+}
+
 #[allow(clippy::manual_range_contains)]
 /// Absolute salinity of seawater from given density, Conservative
 /// Temperature, and pressure.