[Bug 2931407]: Clarified semantics of division and remainder operators.

1 files changed, 14 insertions, 1 deletions

diff --git a/doc/expr.n b/doc/expr.n
index 177e127..dbc9026 100644
--- a/doc/expr.n
+++ b/doc/expr.n
@@ -131,7 +131,20 @@ Multiply, divide, remainder.  None of these operators may be
 applied to string operands, and remainder may be applied only
 to integers.
 The remainder will always have the same sign as the divisor and
-an absolute value smaller than the divisor.
+an absolute value smaller than the absolute value of the divisor.
+.RS
+.PP
+When applied to integers, the division and remainder operators can be
+considered to partition the number line into a sequence of equal-sized
+adjacent non-overlapping pieces where each piece is the size of the divisor;
+the division result identifies which piece the divisor lay within, and the
+remainder result identifies where within that piece the divisor lay. A
+consequence of this is that the result of
+.QW "-57 \fB/\fR 10"
+is always -6, and the result of
+.QW "-57 \fB%\fR 10"
+is always 3.
+.RE
 .TP 20
 \fB+\0\0\-\fR
 Add and subtract.  Valid for any numeric operands.