Fixing nrps calculation

radixio/spectrum.cc

+#include <cmath>
+
 #include "radixio/spectrum.hh"
 
 namespace radix
@@ -17,7 +19,7 @@ short Spectrum::nrps() const
     }
   }
 
-  short nrps = short((maxChannels / 64) + 1);
+  short nrps = short(ceil((float(maxChannels) / 64.0) + 1.0));
 
   return nrps;
 }