AWK sum all values of a column keeping all floats - awk

Question

I'm using the following code to grep the lines that im interested in, keep only the last ones and sum over column nine:
grep -n -49 'FINAL BlaBla' output |tail -9 | awk 'BEGIN {SUM=0}; {SUM=SUM+$9}; END {printf "%.3f\n" SUM}.
However the sum over column 9 returns 0,000
the selected lines look as follows
84- C -3.42056726 +1 -0.82831327 +1 1.52743549 +1 0.5647
85- N -4.78612760 +1 -1.01185554 +1 1.58894854 +1 -0.5837
86- C -5.19047197 +1 -2.20130686 +1 2.06176295 +1 0.3890
87- N -4.42537785 +1 -3.22689397 +1 2.47304603 +1 -0.4775
88- C -3.03532546 +1 -2.98933854 +1 2.38795560 +1 0.3686
89- N -2.51737448 +1 -1.78267672 +1 1.92262528 +1 -0.5526
90- Cl -6.86455806 +1 -2.45050886 +1 2.15229544 +1 0.0934
91- N -2.24043582 +1 -3.93651444 +1 2.76082642 +1 0.0890
92- N -2.94053526 +1 0.36941710 +1 1.06455738 +1 -0.3274
I can't find out where the mistake is.
I also tried to sum over $1 and I correctly obtain 792,000 but when I sum over $3 I get 31,000 ...
what's wrong?

Answer 1

I think the problem lies in the missing comma in your printf expression:
$ awk 'BEGIN {SUM=0}; {SUM=SUM+$9}; END {printf "%.3f\n", SUM}' file
# ^
# comma!
-0.436
Note by the way that there is no need to set the variable to zero, since this is the default. So drop the BEGIN {} block and leave to just:
awk '{sum+=$9}; END {printf "%.3f\n", sum}' file
For the other fields:
$ awk '{sum+=$nvar}; END {printf "%.3f\n", sum}' nvar=1 file
792.000
$ awk '{sum+=$nvar}; END {printf "%.3f\n", sum}' nvar=3 file
-35.421
$ awk '{sum+=$nvar}; END {printf "%.3f\n", sum}' nvar=9 file
-0.436
Why wasn't it working?
From The GNU Awk user's guide 5.5.1 Introduction to the printf Statement:
A simple printf statement looks like this:
printf format, item1, item2, …
As for print, the entire list of arguments may optionally be enclosed
in parentheses
The difference between printf and print is the format argument. This
is an expression whose value is taken as a string; it specifies how to
output each of the other arguments. It is called the format string.
The format string is very similar to that in the ISO C library
function printf(). Most of format is text to output verbatim.
Scattered among this text are format specifiers—one per item. Each
format specifier says to output the next item in the argument list at
that place in the format.
So if you don't use commas to call the fields you get this error:
$ awk 'BEGIN {printf "%.3f" 3}'
awk: cmd. line:1: fatal: not enough arguments to satisfy format string
`%.3f3'
^ ran out for this one
Using them it works!
$ awk 'BEGIN {printf "%.3f", 3}'
3.000