Dash as multiplication sign in older texts

[DrDu]

Sometimes I have seen a dash (-) being used as multiplication sign, usually in connection with units. Does anybody know where this strange custom has it's origin?

 

[Hurkyl]

Sometimes I have seen a dash (-) being used as multiplication sign, usually in connection with units. Does anybody know where this strange custom has it's origin?

It's a hyphen: it's taking the two words and amalgamating them into a single hyphenated word.

 

[DrDu]

Nevertheless I find units like "mg m^-3-years" very confusing.

 

[Studiot]

There is sense in that statement.

Consider some poor Physics Forum member typing here

mg / m³ years

or

mg / m³ /years

or

(mg / m³) years

you try typing this and then have a doubt as to whether the years should be on the top or the bottom. Or whether others will interpret it as you have.

The hyphen is a good way to make certain.

Another way is simply to coin a new unit.

eg

Newton-metres = joules

go well