Added adiabatic_temperature_gradient function

src/oceanography.c

@@ -179,3 +179,16 @@ double specific_heat(double salinity, double temperature, double pressure)
 
     return cp0 + cp1 + cp2;
 }
+
+double adiabatic_temperature_gradient(double salinity, double temperature,
+                                      double pressure)
+{
+    salinity = salinity - 35.0;
+
+    return (((-2.1687e-16 * temperature + 1.8676e-14) * temperature -
+            4.6206e-13) * pressure + ((2.7759e-12 * temperature - 1.1351e-10) *
+            salinity + ((-5.4481e-14 * temperature + 8.733e-12) * temperature -
+            6.7795e-10) * temperature + 1.8741e-8)) * pressure + (-4.2393e-8 *
+            temperature + 1.8932e-6) * salinity + ((6.6228e-10 * temperature -
+            6.836e-8) * temperature + 8.5258e-6) * temperature + 3.5803e-5;
+}

src/oceanography.h

@@ -8,5 +8,7 @@ double specific_volume_anomaly(double salinity, double temperature,
 double depth(double pressure, double latitude);
 double freezing_point(double salinity, double pressure);
 double specific_heat(double salinity, double temperature, double pressure);
+double adiabatic_temperature_gradient(double salinity, double temperature,
+                                      double pressure);
 
 #endif

tests/check_oceanography.c

@@ -82,6 +82,18 @@ START_TEST(test_specific_heat)
 }
 END_TEST
 
+START_TEST(test_adiabatic_temperature_gradient)
+{
+    ck_assert(cmp_double(adiabatic_temperature_gradient(25, 0, 0),
+                         1.687100e-05));
+    ck_assert(cmp_double(adiabatic_temperature_gradient(30, 20, 9000),
+                         2.416120e-04));
+    ck_assert(cmp_double(adiabatic_temperature_gradient(40, 40, 10000),
+                         3.255976e-04));
+}
+END_TEST
+
+
 Suite *oceanography_suite(void)
 {
     Suite *s = suite_create("Oceanography");
@@ -92,6 +104,7 @@ Suite *oceanography_suite(void)
     tcase_add_test(tc_core, test_depth);
     tcase_add_test(tc_core, test_freezing_point);
     tcase_add_test(tc_core, test_specific_heat);
+    tcase_add_test(tc_core, test_adiabatic_temperature_gradient);
     suite_add_tcase(s, tc_core);
 
     return s;