reading frequency group with underscore

inversion.cpp

@@ -108,7 +108,7 @@ int inversion(const GmshFem& gmshFem)
             for (unsigned int f = 0; f < n_freq; f++)
             {
                 std::string suffix_f = std::to_string(f);
-                if(!gmshFem.userDefinedParameter(freq_idx[f], "frequency"+suffix_g+suffix_f))
+                if(!gmshFem.userDefinedParameter(freq_idx[f], "frequency"+suffix_g+"_"+suffix_f))
                 {
                     freq_idx[f] = f;
                     msg::warning << "Frequency index #"+suffix_f+" for group #" + suffix_g + " could not be found. Index = " << f << "(default)." << msg::endl;

specific/configuration/green0_preconditioner.h

@@ -16,6 +16,7 @@
 #include "line_acquisition.h"
 #include "rectangular_acquisition.h"
 #include "circular_acquisition.h"
+#include "flexible_acquisition.h"
 
 using namespace gmshfem;
 using namespace gmshfem::common;