# Staff Line Thickness

(I edited my first posting in order to be more precise)

In “Engraving Options/Staves” one can set the Staff line thickness.
It is possible to choose between some values expressed in division, for example 1/8 or 1/4.
It is also possible to write your own values like 1/10 (for 0.1) or 3/20 (for 0.15)
It is also possible to directly write 0.1 and Dorico converts it to 1/10.
At first sight it seems also that Dorico converts 0.125 correctly to 1/8.
But hovering with the mouse on the arrow Dorico shows the decimal value 0.13 for 1/8
It seems as if Dorico can only use only two decimal after the comma.

1. Why does Dorico shows divisions if they cannot be calculted exactly?

2. It is possible to set the value 0.
The score changes then and the staff lines are quite thin, but what is the spaces value when 0 is choosed?
Hovering with the mouse over the arrows shows nothing.

3. It is possible to set negative values.
-1/8 changes the thickness to something like + 9/50
-1/4 seems to be similar to -1/8
From -3/8 each new negative value shortens the bar line!
Is it the way it is supposed to be?

All these questions are essentially out of curiosity, I can live with what Dorico offers in this field, I am just trying to understand what the program does.

Internally Dorico uses rational numbers, i.e. fractions, for everything, so even if you enter a decimal number, Dorico converts it into a rational number; however, there is always the risk of some loss of precision when converting from rational numbers to floating point numbers, and indeed this is the reason why when you type in 0.125 you later see 0.13 in the tool tip, because the converted floating point numbers are shown to a maximum of two decimal places.

You shouldn’t be able to set either zero or negative values for this value, so we’ll try to tighten this up in the future.

Thank you.