Change the sign of a number.
The UnaryExpr is a unary operator which changes the sign of
a Number. It takes as argument a SetExpr which may
also be a node set. In that case, it tries to convert the value of the
respective node of the last document in the result set into a numeric value and
changes the sign of that number
It corresponds to the expression UnaryExpr defined in
XPath, Section 2.4, Rule
3.
This is simply a Number, the numeric value -3.
-3
Change the sign of the numeric value -3.
-(-3)
Subtract the year of birth of the last patient from the numeric value
-2001 (no application of UnaryExpr):
-2001-patient/born
Subtract the year of birth of the last patient from 2001 and change it in a negative value:
-(2001-patient/born)
AdditiveExpr |