an example of parallel calculation of metrics

[Jay Norwood via Digitalmars-d-learn]

On Wednesday, 30 September 2015 at 22:24:25 UTC, Jay Norwood 
wrote:
> // various metric definitions
> // the Tuples could also define names for each member and use 
> the names here in the metrics.
> long met1( TI m){ return m[0] + m[1] + m[2]; }
> long met2( TI m){ return m[1] + m[2] + m[3]; }
> long met3( TI m){ return m[0] - m[1] + m[2]; }
> long met4( TI m){ return m[0] + m[1] - m[2]; }
>

should use reference parameters here:
long met1( ref TI m){ return m[0] + m[1] + m[2]; }
long met2( ref TI m){ return m[1] + m[2] + m[3]; }
long met3( ref TI m){ return m[0] - m[1] + m[2]; }
long met4( ref TI m){ return m[0] + m[1] - m[2]; }