Changeset 2221 in ntrip for trunk/BNC/bncutils.cpp

Timestamp:

Jan 12, 2010, 8:36:29 AM (15 years ago)

Author:

mervart

Message:

* empty log message *

File:

• trunk/BNC/bncutils.cpp (modified) (1 diff)

trunk/BNC/bncutils.cpp

@@ -243 +243 @@
            + sinPhi        * xyz[2];
 }
+
+// Fourth order Runge-Kutta numerical integrator for ODEs
+////////////////////////////////////////////////////////////////////////////
+ColumnVector rungeKutta4(
+  double xi,              // the initial x-value
+  const ColumnVector& yi, // vector of the initial y-values
+  double dx,              // the step size for the integration
+  ColumnVector (*der)(double x, const ColumnVector& y)
+                          // A pointer to a function that computes the 
+                          // derivative of a function at a point (x,y)
+                         ) {
+
+  ColumnVector k1 = der(xi       , yi       ) * dx;
+  ColumnVector k2 = der(xi+dx/2.0, yi+k1/2.0) * dx;
+  ColumnVector k3 = der(xi+dx/2.0, yi+k2/2.0) * dx;
+  ColumnVector k4 = der(xi+dx    , yi+k3    ) * dx;
+
+  ColumnVector yf = yi + k1/6.0 + k2/3.0 + k3/3.0 + k4/6.0;
+  
+  return yf;
+}
+