Update WMM.hpp

corsika/media/WMM.hpp

@@ -6,27 +6,14 @@
  * the license.
  */
 
+#include <boost/filesystem.hpp>
+#include <boost/math/special_functions/factorials.hpp>
 #include <boost/math/special_functions/legendre.hpp>
+
 #include <cmath>
 #include <corsika/framework/core/Logging.hpp>
 #include <corsika/framework/utility/CorsikaData.hpp>
 #include <fstream>
-#include <iostream>
-using namespace std;
-
-double factorial(int n) {
-  double factorial = 1;
-  if (n < 0) {
-    CORSIKA_LOG_ERROR("Factorial of a negative number does not exist.");
-    abort();
-  }
-  else {
-    for(int i = 1; i <= n; ++i) {
-      factorial *= i;
-    }
-  }
-  return factorial;
-}
 
 namespace corsika {
   MagneticFieldVector get_wmm(const CoordinateSystemPtr Cs, const double year, const LengthType altitude, const double latitude, const double longitude) {
@@ -34,13 +21,13 @@ namespace corsika {
       CORSIKA_LOG_ERROR("Year has to be between 2020 and 2025.");
       abort();
     }
-    if (altitude < -10_km || altitude > 3000_km) {
+    if (altitude < -1_km || altitude > 850_km) {
       CORSIKA_LOG_WARN("Altitude should be between -10_km and 3000_km.");
     }
     if (latitude < -90 || latitude > 90) {
       CORSIKA_LOG_ERROR("Latitude has to be between -90 and 90 degree.");
       abort();
-    } else if (latitude < -82 || latitude > 82) {
+    } else if (latitude < -89.992 || latitude > 89.992) {
       CORSIKA_LOG_WARN("Latitude is close to the poles.");
     }
     if (longitude < -180 || longitude > 180) {
@@ -48,14 +35,13 @@ namespace corsika {
       abort();
     }
     
-    double lat_geo = latitude * constants::pi / 180;
-    double lon = longitude * constants::pi / 180;
+    const double lat_geo = latitude * constants::pi / 180;
+    const double lon = longitude * constants::pi / 180;
   
     // Transform into spherical coordinates
-    const LengthType A = 6378137_m;
     const double f = 1 / 298.257223563;
     const double e_squared = f * (2 - f);
-    LengthType R_c = A / sqrt(1 - e_squared * pow(sin(lat_geo), 2));
+    LengthType R_c = constants::EarthRadius::Equatorial / sqrt(1 - e_squared * pow(sin(lat_geo), 2));
     LengthType p = (R_c + altitude) * cos(lat_geo);
     LengthType z = sin(lat_geo) * (altitude + R_c * (1 - e_squared));
     LengthType r = sqrt(p * p + z * z);
@@ -63,49 +49,45 @@ namespace corsika {
     
     const int length = 90;
     double epoch, g[length], h[length], g_dot[length], h_dot[length];
-    char model_name[7];
-    char release_date[10];
+    std::string model_name;
+    std::string release_date;
     int n[length], m[length];
-    ifstream infile;
     
     // Read in coefficients
     boost::filesystem::path const path = corsika::corsika_data("GeoMag/WMM.COF");
-    char mdfile[path.generic_string().size() + 1];
-    strcpy(mdfile, path.generic_string().c_str());    //name and path of model file
-    infile.open(mdfile);
+    boost::filesystem::ifstream file(path, std::ios::in);
     // Exit if file opening failed
-    if (!infile.is_open()){
+    if (!file.is_open()){
       CORSIKA_LOG_ERROR("Failed opening WMM.COF.");
       abort();
     }
     
-    infile >> epoch >> model_name >> release_date;
+    file >> epoch >> model_name >> release_date;
     for (int i = 0; i < length; i++) {
-      infile >> n[i] >> m[i] >> g[i] >> h[i] >> g_dot[i] >> h_dot[i];
+      file >> n[i] >> m[i] >> g[i] >> h[i] >> g_dot[i] >> h_dot[i];
       // Time interpolation
       g[i] = g[i] + (year - epoch) * g_dot[i];
       h[i] = h[i] + (year - epoch) * h_dot[i];
     }
-    infile.close();
+    file.close();
     
     double legendre, next_legendre, derivate_legendre;
     double magneticfield[3] = {0, 0, 0};
     
     for (int j = 0; j < length; j++) {
-      // cout << assoc_legendre(n[0], m[0], sin(lat_sph)) << endl;
       legendre = boost::math::legendre_p(n[j], m[j], sin(lat_sph));
       next_legendre = boost::math::legendre_p(n[j] + 1, m[j], sin(lat_sph));
       
       // Schmidt semi-normalization and Condon-Shortley phase term
       if (m[j] > 0) {
-        legendre *= sqrt(2 * factorial(n[j] - m[j]) / factorial(n[j] + m[j])) * pow(-1, m[j]);
-        next_legendre *= sqrt(2 * factorial(n[j] + 1 - m[j]) / factorial(n[j] + 1 + m[j])) * pow(-1, m[j]);
+        legendre *= sqrt(2 * boost::math::factorial<double>(n[j] - m[j]) / boost::math::factorial<double>(n[j] + m[j])) * pow(-1, m[j]);
+        next_legendre *= sqrt(2 * boost::math::factorial<double>(n[j] + 1 - m[j]) / boost::math::factorial<double>(n[j] + 1 + m[j])) * pow(-1, m[j]);
       }
       derivate_legendre = (n[j] + 1) * tan(lat_sph) * legendre - sqrt(pow(n[j] + 1, 2) - pow(m[j], 2)) / cos(lat_sph) * next_legendre;
       
-      magneticfield[0] += pow(constants::EarthRadius::Mean / r, n[j] + 2) * (g[j] * cos(m[j] * lon) + h[j] * sin(m[j] * lon)) * derivate_legendre;
-      magneticfield[1] += pow(constants::EarthRadius::Mean / r, n[j] + 2) * m[j] * (g[j] * sin(m[j] * lon) - h[j] * cos(m[j] * lon)) * legendre;
-      magneticfield[2] += (n[j] + 1) * pow(constants::EarthRadius::Mean / r, n[j] + 2) * (g[j] * cos(m[j] * lon) + h[j] * sin(m[j] * lon)) * legendre;
+      magneticfield[0] += pow(constants::EarthRadius::Geomagnetic_reference / r, n[j] + 2) * (g[j] * cos(m[j] * lon) + h[j] * sin(m[j] * lon)) * derivate_legendre;
+      magneticfield[1] += pow(constants::EarthRadius::Geomagnetic_reference / r, n[j] + 2) * m[j] * (g[j] * sin(m[j] * lon) - h[j] * cos(m[j] * lon)) * legendre;
+      magneticfield[2] += (n[j] + 1) * pow(constants::EarthRadius::Geomagnetic_reference / r, n[j] + 2) * (g[j] * cos(m[j] * lon) + h[j] * sin(m[j] * lon)) * legendre;
     }
     magneticfield[0] *= -1;
     magneticfield[1] /= cos(lat_sph);
@@ -119,4 +101,4 @@ namespace corsika {
     
     return MagneticFieldVector{Cs, magneticfield_geo[0] * 1_nT, magneticfield_geo[1] * 1_nT, magneticfield_geo[2] * -1_nT};
   }
-}
\ No newline at end of file
+}