Changeset: 5a2dd25c1de7 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB/rev/5a2dd25c1de7
Modified Files:
gdk/gdk_aggr.c
Branch: Jan2022
Log Message:
Updated some comments.
diffs (44 lines):
diff --git a/gdk/gdk_aggr.c b/gdk/gdk_aggr.c
--- a/gdk/gdk_aggr.c
+++ b/gdk/gdk_aggr.c
@@ -1820,7 +1820,17 @@ BATprod(void *res, int tp, BAT *b, BAT *
} \
} while (0)
-/* calculate group averages with optional candidates list */
+/* There are three functions that are used for calculating averages.
+ * The first one (BATgroupavg) returns averages as a floating point
+ * value, the other two (BATgroupavg3 and BATgroupavg3combine) work
+ * together to return averages in the domain type (which should be an
+ * integer type). */
+
+/* Calculate group averages with optional candidates list. The average
+ * that is calculated is returned in a dbl, independent of the type of
+ * the input. The average is calculated exactly, so not in a floating
+ * point which could potentially losse bits during processing
+ * (e.g. average of 2**62 and a billion 1's). */
gdk_return
BATgroupavg(BAT **bnp, BAT **cntsp, BAT *b, BAT *g, BAT *e, BAT *s, int tp,
bool skip_nils, bool abort_on_error, int scale)
{
@@ -2014,13 +2024,14 @@ BATgroupavg(BAT **bnp, BAT **cntsp, BAT
return GDK_FAIL;
}
-/* An exact numeric average of a bunch of values consists of three parts: the
- * average rounded down (towards minus infinity), the number of values that
- * participated in the calculation, and the remainder. The remainder is in the
- * range 0 (inclusive) to count (not inclusive). BATgroupavg3 calculates these
- * values for each given group. The function below, BATgroupavg3combine,
- * combines averages calculated this way to correct, rounded or truncated
- * towards zero (depending on the symbol TRUNCATE_NUMBERS) averages. */
+/* An exact numeric average of a bunch of values consists of three
+ * parts: the average rounded down (towards minus infinity), the number
+ * of values that participated in the calculation, and the remainder.
+ * The remainder is in the range 0 (inclusive) to count (not inclusive).
+ * BATgroupavg3 calculates these values for each given group. The
+ * function below, BATgroupavg3combine, combines averages calculated
+ * this way to correct averages by rounding or truncating towards zero
+ * (depending on the symbol TRUNCATE_NUMBERS). */
gdk_return
BATgroupavg3(BAT **avgp, BAT **remp, BAT **cntp, BAT *b, BAT *g, BAT *e, BAT
*s, bool skip_nils)
{
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