adding diam2rad utility function with test

Author: zdaq12

src/pypartmc.cpp

@@ -211,6 +211,11 @@ PYBIND11_MODULE(_PyPartMC, m) {
         "Convert geometric radius (m) to mass-equivalent volume for spherical particles."
     );
 
+    m.def(
+        "diam2rad", &diam2rad, py::return_value_policy::copy,
+        "Convert diameter (m) to radius (m)."
+    );
+
     m.attr("__version__") = MACRO_STRINGIFY(VERSION_INFO);
 
     m.attr("__all__") = py::make_tuple(
@@ -230,6 +235,7 @@ PYBIND11_MODULE(_PyPartMC, m) {
         "histogram_2d",
         "sphere_vol2rad",
         "rad2diam",
-        "sphere_rad2vol"
+        "sphere_rad2vol",
+        "diam2rad"
     );
 }

src/util.F90

@@ -43,4 +43,12 @@ subroutine f_sphere_rad2vol(rad, v) bind(C)
 
 end subroutine
 
+subroutine f_diam2rad(d, rad) bind(C)
+   real(c_double), intent(in) :: d
+   real(c_double), intent(out) :: rad
+
+   rad = diam2rad(d)
+
+end subroutine
+
 end module

src/util.hpp

@@ -10,6 +10,7 @@ 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*);
+extern "C" void f_diam2rad(const double*, double*);
 
 auto pow2_above(int n) {
     int res;
@@ -35,5 +36,11 @@ double sphere_rad2vol(double rad) {
     return v;
 }
 
+double diam2rad(double d) {
+    double rad;
+    f_diam2rad(&d, &rad);
+    return rad;
+}
+
 extern "C" double py_deg2rad(double);
 

tests/test_util.py

@@ -56,3 +56,14 @@ def test_sphere_rad2vol():
 
         # assert
         np.testing.assert_almost_equal(vol, (4/3)*np.pi*(arg)**3)
+
+    @staticmethod
+    def test_diam2rad():
+        # arrange
+        arg = 1e-6
+
+        # act
+        rad = ppmc.diam2rad(arg)
+
+        # assert
+        assert rad == arg/2