To avoid type conversion.

src/cache.h

@@ -369,9 +369,9 @@ __attribute__((always_inline)) INLINE void cache_read_two_partial_cells_sorted(
   }
 
 #ifdef SWIFT_DEBUG_CHECKS
-  const double shift_threshold_x = 4. * ci->width[0] * (1. + 2.*space_maxreldx);
-  const double shift_threshold_y = 4. * ci->width[1] * (1. + 2.*space_maxreldx);
-  const double shift_threshold_z = 4. * ci->width[2] * (1. + 2.*space_maxreldx);
+  const float shift_threshold_x = 4. * ci->width[0] * (1. + 2.*space_maxreldx);
+  const float shift_threshold_y = 4. * ci->width[1] * (1. + 2.*space_maxreldx);
+  const float shift_threshold_z = 4. * ci->width[2] * (1. + 2.*space_maxreldx);
 
   /* Make sure that particle positions have been shifted correctly. */
   for (int i = 0; i < ci_cache_count; i++) {