adding sphere_vol2rad utility function with test

Author: zdaq12

src/pypartmc.cpp

@@ -196,6 +196,11 @@ PYBIND11_MODULE(_PyPartMC, m) {
         "Return the least power-of-2 that is at least equal to n."
     );
 
+    m.def(
+        "sphere_vol2rad", &sphere_vol2rad, py::return_value_policy::copy,
+        "Convert mass-equivalent volume (m^3) to geometric radius (m) for spherical particles."
+    );
+
     m.attr("__version__") = MACRO_STRINGIFY(VERSION_INFO);
 
     m.attr("__all__") = py::make_tuple(
@@ -212,6 +217,7 @@ PYBIND11_MODULE(_PyPartMC, m) {
         "run_part",
         "pow2_above",
         "histogram_1d",
-        "histogram_2d"
+        "histogram_2d",
+        "sphere_vol2rad"
     );
 }

src/util.F90

@@ -19,4 +19,12 @@ subroutine py_pow2_above(n, res) bind(C)
    res = pow2_above(n)
 end subroutine
 
+subroutine f_sphere_vol2rad(v, rad) bind(C)
+   real(c_double), intent(in) :: v
+   real(c_double), intent(out) :: rad
+
+   rad = sphere_vol2rad(v)
+
+end subroutine
+
 end module

src/util.hpp

@@ -7,12 +7,19 @@
 #pragma once
 
 extern "C" void py_pow2_above(int*, int*);
+extern "C" void f_sphere_vol2rad(const double*, double*);
 
 auto pow2_above(int n) {
     int res;
     py_pow2_above(&n, &res);
     return res;
 }
 
+double sphere_vol2rad(double v) {
+    double rad;
+    f_sphere_vol2rad(&v, &rad);
+    return rad;
+}
+
 extern "C" double py_deg2rad(double);
 

tests/test_util.py

@@ -4,6 +4,7 @@
 # Authors: https://github.com/open-atmos/PyPartMC/graphs/contributors                              #
 ####################################################################################################
 
+import numpy as np
 import PyPartMC as ppmc
 
 
@@ -23,3 +24,13 @@ def test_pow2_above():
     def test_deg2rad():
         pass
 
+    @staticmethod
+    def test_sphere_vol2rad():
+        # arrange
+        arg = (4/3)*np.pi*(1e-6)**3
+
+        # act
+        rad = ppmc.sphere_vol2rad(arg)
+
+        # assert
+        np.testing.assert_almost_equal(1e-6, rad)