From 4a4f2124f2f8f83b6cef98a93e5fbad1c9584921 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Teemu=20S=C3=A4ilynoja?=
 <33978952+TeemuSailynoja@users.noreply.github.com>
Date: Thu, 27 Mar 2025 12:44:36 +0200
Subject: [PATCH 1/2] Update log_sum_exp

Add behaviour to the function in the corner cases of infinite values or empty input.
---
 R/misc.R | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/R/misc.R b/R/misc.R
index 02c8df6a..da26fd0f 100644
--- a/R/misc.R
+++ b/R/misc.R
@@ -1,4 +1,4 @@
-# initialize a named list
+  # initialize a named list
 # @param names names of the elements
 # @param values optional values of the elements
 named_list <- function(names, values = NULL) {
@@ -209,9 +209,16 @@ escape_all <- function(x) {
 
 # numerically stable version of log(sum(exp(x)))
 log_sum_exp <- function(x) {
-  max <- max(x)
-  sum <- sum(exp(x - max))
-  max + log(sum)
+  max <- max(as.numeric(x), warnings = FALSE)
+  if (max == -Inf) {
+    res <- 0
+  } else if (max == Inf) {
+    res <- Inf
+  } else {
+    sum <- sum(exp(x - max))
+    res <- max + log(sum)
+  }
+  res
 }
 
 # simple version of destructuring assignment

From fcec2206b66739adcdd033220b688520397d0d56 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Teemu=20S=C3=A4ilynoja?= <teemu.sailynoja@gmail.com>
Date: Thu, 27 Mar 2025 19:04:28 +0200
Subject: [PATCH 2/2] Test log_sum_exp

---
 tests/testthat/test-log_sum_exp.R | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 tests/testthat/test-log_sum_exp.R

diff --git a/tests/testthat/test-log_sum_exp.R b/tests/testthat/test-log_sum_exp.R
new file mode 100644
index 00000000..3e343938
--- /dev/null
+++ b/tests/testthat/test-log_sum_exp.R
@@ -0,0 +1,21 @@
+# Ensure that log_sum_exp agrees with expected behaviour from log(sum(exp(x)))
+test_that("log_sum_exp of for x containing Inf is Inf", {
+  x <- c(Inf, 1)
+  expect_equal(log_sum_exp(x), Inf)
+})
+
+test_that("log_sum_exp of -Inf is -Inf", {
+  x <- c(-Inf, -Inf)
+  expect_equal(log_sum_exp(x), -Inf)
+})
+
+test_that("log_sum_exp of empty input is -Inf", {
+  x <- numeric(0)
+  expect_equal(log_sum_exp(x), -Inf)
+})
+
+test_that("log_sum_exp works", {
+  set.seed(1)
+  x <- log(runif(10))
+  expect_equal(log_sum_exp(x), log(sum(exp(x))))
+})