From 159d5cd4ab2ae4ce873f14901fcd81706940e86d Mon Sep 17 00:00:00 2001
From: Mo Chen <sth4nth@gmail.com>
Date: Sat, 26 Aug 2017 19:35:50 +0800
Subject: [PATCH] update log1pexp log1mexp

---
 common/log1mexp.m | 8 ++++----
 common/log1pexp.m | 9 +++++----
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/common/log1mexp.m b/common/log1mexp.m
index 3892c70..51918e1 100644
--- a/common/log1mexp.m
+++ b/common/log1mexp.m
@@ -1,7 +1,7 @@
 function y = log1mexp(x)
-% Accurately compute y = log(1-exp(-x))
+% Accurately compute y = log(1-exp(x))
 % reference: Accurately Computing log(1-exp(-|a|)) Martin Machler
 y = x;
-i = x > log(2);
-y(i) = log1p(-exp(-x(i)));
-y(~i) = log(-expm1(-x(~i)));
+i = x < -log(2);
+y(i) = log1p(-exp(x(i)));
+y(~i) = log(-expm1(x(~i)));
diff --git a/common/log1pexp.m b/common/log1pexp.m
index 7ad0b9d..10096e5 100644
--- a/common/log1pexp.m
+++ b/common/log1pexp.m
@@ -1,7 +1,8 @@
 function y = log1pexp(x)
 % Accurately compute y = log(1+exp(x))
-% reference: Accurately Computing log(1-exp(|a|)) Martin Machler
-seed = 33.3;
+% reference: Accurately Computing log(1-exp(-|a|)) Martin Machler
 y = x;
-idx = x<seed;
-y(idx) = log1p(exp(x(idx)));
\ No newline at end of file
+i = x > 18;
+j = i & (x <= 33.3);
+y(~i) = log1p(exp(x(~i)));
+y(j) = x(j)+exp(-x(j));