diff --git a/src/algorithms/libs/rtklib/rtklib_pntpos.cc b/src/algorithms/libs/rtklib/rtklib_pntpos.cc
index 69f093703..13ec3434b 100644
--- a/src/algorithms/libs/rtklib/rtklib_pntpos.cc
+++ b/src/algorithms/libs/rtklib/rtklib_pntpos.cc
@@ -54,6 +54,7 @@
 #include "rtklib_ephemeris.h"
 #include "rtklib_ionex.h"
 #include "rtklib_sbas.h"
+#include <iostream>
 
 /* pseudorange measurement error variance ------------------------------------*/
 double varerr(const prcopt_t *opt, double el, int sys)
@@ -163,7 +164,9 @@ double prange(const obsd_t *obs, const nav_t *nav, const double *azel,
     	        }
     	    else if((obs->code[i] == CODE_NONE) && (obs->code[j] != CODE_NONE))
     	        {
-    	    	    P2 += P2_C2; /* C2->P2 */
+    	            std::cout << "P1_P2 = " << P1_P2 << std::endl;
+    	            std::cout << "P2_C2 = " << P2_C2 << std::endl;
+    	            P2 += P2_C2; /* C2->P2 */
     	    	    PC = P2 - gamma_ * P1_P2 / (1.0 - gamma_);
     	        }
     	    /* dual-frequency */