A summation expression has the form
sum [<var> = <start> : <end>] <expression>
var is treated as an integer variable that takes on successive integral
values from start to end. For each of these, the current value of
expression is added to a running total whose final value becomes the value
of the summation expression.
Examples:
print sum [i=1:10] i
55.
# Equivalent to plot 'data' using 1:($2+$3+$4+$5+$6+...)
plot 'data' using 1 : (sum [col=2:MAXCOL] column(col))
It is not necessary that expression contain the variable var.
Although start and end can be specified as variables or expressions,
their value cannot be changed dynamically as a side-effect of carrying
out the summation. If end is less than start then the value of the
summation is zero.
Build Daemon user
2016-02-12