Trendarith.cc: Check that memType of field1 and field4 are the same.

src/Trendarith.cc

@@ -33,7 +33,7 @@ add_trend(double zj, const Varray<T> &v1, const Varray<double> &v2, const Varray
 static void
 add_trend(double zj, const Field &field1, const Field &field2, const Field &field3, Field &field4)
 {
-  if (field1.memType != field2.memType) cdo_abort("Interal error, memType of field1 and field2 differ!");
+  if (field1.memType != field4.memType) cdo_abort("Interal error, memType of field1 and field2 differ!");
 
   if (field1.memType == MemType::Float)
     add_trend(zj, field1.vec_f, field2.vec_d, field3.vec_d, field4.vec_f, field1.size, field1.missval);
@@ -54,7 +54,7 @@ sub_trend(double zj, const Varray<T> &v1, const Varray<double> &v2, const Varray
 static void
 sub_trend(double zj, const Field &field1, const Field &field2, const Field &field3, Field &field4)
 {
-  if (field1.memType != field2.memType) cdo_abort("Interal error, memType of field1 and field2 differ!");
+  if (field1.memType != field4.memType) cdo_abort("Interal error, memType of field1 and field2 differ!");
 
   if (field1.memType == MemType::Float)
     sub_trend(zj, field1.vec_f, field2.vec_d, field3.vec_d, field4.vec_f, field1.size, field1.missval);