The ROUNDMODE
variable provides
program level control over the rounding mode.
The correspondence between ROUNDMODE
and the IEEE
rounding modes is shown in tablegawkroundingmodes.
Rounding Mode  IEEE Name  ROUNDMODE


Round to nearest, ties to even  roundTiesToEven  "N" or "n"

Round toward plus Infinity  roundTowardPositive  "U" or "u"

Round toward negative Infinity  roundTowardNegative  "D" or "d"

Round toward zero  roundTowardZero  "Z" or "z"

Round to nearest, ties away from zero  roundTiesToAway  "A" or "a"

Table 15.4: gawk Rounding Modes
ROUNDMODE
has the default value "N"
,
which selects the IEEE754 rounding mode roundTiesToEven
.
In Table 15.4, "A"
is listed to select the IEEE754 mode
roundTiesToAway
. This is only available
if your version of the MPFR library supports it; otherwise setting
ROUNDMODE
to this value has no effect. See Rounding Mode,
for the meanings of the various rounding modes.
Here is an example of how to change the default rounding behavior of
printf
's output:
$ gawk M v ROUNDMODE="Z" 'BEGIN { printf("%.2f\n", 1.378) }'  1.37