I tried to use the Interrelation "Concatenate" for subtraction of two variables.

It worked for some variables but gave the wrong sign for some other calculations.

I.e.

Concatenate<csp_float,DIM,minus> diff_temperature( p_ref, "diff temperature","temperature","previous temperature" );

gives the wrong sign.

If I give the last argument a name which comes later in the alphabet it works.

i.e.

Concatenate<csp_float,DIM,minus> diff_temperature( p_ref, "diff temperature","temperature","x previous temperature" );

I am not quite sure why the operand_list of an interrelation is filled like this:

operand_list[ string(var) ] = op;

but could this be the problem?

Or did I use Concatenate incorrectly?

Thanks for help or clarifications,

Philipp