doc: document division by zero.

* txr.1: Document that floor, mod, floor-rem and other
functions in this family throw an exception if the
divisor is zero.

1 files changed, 17 insertions, 0 deletions

diff --git a/txr.1 b/txr.1
index 4f580588..9571db98 100644
--- a/txr.1
+++ b/txr.1
@@ -35805,6 +35805,11 @@ If the
 .meta divisor
 is omitted, it defaults to 1.
 
+A zero
+.meta divisor
+results in an exception of type
+.codn numeric-error .
+
 If both inputs are integers,
 the result is of type integer.
 
@@ -35897,6 +35902,13 @@ then generalized into the floating point domain. For instance the expression
 yields a residue of 0.25 because 0.5 "goes into" 0.75 only
 once, with a "remainder" of 0.25.
 
+If
+.meta divisor
+is zero,
+.code mod
+throws an exception of type
+.codn numeric-error .
+
 .coNP Functions @, trunc-rem @, floor-rem @ ceil-rem and @ round-rem
 .synb
 .mets (trunc-rem < dividend <> [ divisor ])
@@ -35935,6 +35947,11 @@ value obeys the following identity:
 .mets (eql < remainder (- < dividend >> (* divisor << quotient )))
 .cble
 
+If
+.meta divisor
+is zero, these functions throw an exception of type
+.codn numeric-error .
+
 .coNP Functions @, sin @, cos @, tan @, asin @, acos @ atan and @ atan2
 .synb
 .mets (sin << radians )