adding sphere_rad2vol utility function with test

Author: zdaq12

src/pypartmc.cpp

@@ -206,6 +206,11 @@ PYBIND11_MODULE(_PyPartMC, m) {
         "Convert radius (m) to diameter (m)."
     );
 
+    m.def(
+        "sphere_rad2vol", &sphere_rad2vol, py::return_value_policy::copy,
+        "Convert geometric radius (m) to mass-equivalent volume for spherical particles."
+    );
+
     m.attr("__version__") = MACRO_STRINGIFY(VERSION_INFO);
 
     m.attr("__all__") = py::make_tuple(
@@ -224,6 +229,7 @@ PYBIND11_MODULE(_PyPartMC, m) {
         "histogram_1d",
         "histogram_2d",
         "sphere_vol2rad",
-        "rad2diam"
+        "rad2diam",
+        "sphere_rad2vol"
     );
 }

src/util.F90

@@ -35,4 +35,12 @@ subroutine f_rad2diam(rad, d) bind(C)
 
 end subroutine
 
+subroutine f_sphere_rad2vol(rad, v) bind(C)
+   real(c_double), intent(in) :: rad
+   real(c_double), intent(out) :: v
+
+   v = sphere_rad2vol(rad)
+
+end subroutine
+
 end module

src/util.hpp

@@ -9,6 +9,7 @@
 extern "C" void py_pow2_above(int*, int*);
 extern "C" void f_sphere_vol2rad(const double*, double*);
 extern "C" void f_rad2diam(const double*, double*);
+extern "C" void f_sphere_rad2vol(const double*, double*);
 
 auto pow2_above(int n) {
     int res;
@@ -28,5 +29,11 @@ double rad2diam(double rad) {
     return  d;
 }
 
+double sphere_rad2vol(double rad) {
+    double v;
+    f_sphere_rad2vol(&rad, &v);
+    return v;
+}
+
 extern "C" double py_deg2rad(double);
 

tests/test_util.py

@@ -45,3 +45,14 @@ def test_rad2diam():
 
         # assert
         assert diam == 2*arg
+
+    @staticmethod
+    def test_sphere_rad2vol():
+        # arrange
+        arg = 1e-6
+
+        # act
+        vol = ppmc.sphere_rad2vol(arg)
+
+        # assert
+        np.testing.assert_almost_equal(vol, (4/3)*np.pi*(arg)**3)