From 98a232cb8c0b4b2dcd69bf00053087ac837b9be5 Mon Sep 17 00:00:00 2001
From: Stephen Chung <schungx@live.com>
Date: Sun, 23 May 2021 11:54:40 +0800
Subject: [PATCH] Prevent exp underflow.

---
 src/packages/math_basic.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/packages/math_basic.rs b/src/packages/math_basic.rs
index cd2c6091..130c36a5 100644
--- a/src/packages/math_basic.rs
+++ b/src/packages/math_basic.rs
@@ -319,6 +319,8 @@ mod decimal_functions {
         if cfg!(not(feature = "unchecked")) {
             if x > Decimal::from_parts(117578, 0, 0, false, 4) {
                 Err(make_err(format!("Exponential overflow: e ** {}", x,)))
+            } else if x < Decimal::from_parts(8, 0, 0, true, 0) {
+                Err(make_err(format!("Exponential underflow: e ** {}", x,)))
             } else {
                 Ok(x.exp())
             }