From bb49d37e32ef3057ce3840a60472dbf389197295 Mon Sep 17 00:00:00 2001
From: Jesse Wheeler <jeswheel@umich.edu>
Date: Thu, 26 Oct 2023 14:32:37 -0400
Subject: [PATCH] Added var check

---
 DESCRIPTION | 2 +-
 NEWS.md     | 4 ++++
 R/arima.R   | 7 ++++++-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/DESCRIPTION b/DESCRIPTION
index 833a512..dee105b 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -1,6 +1,6 @@
 Package: arima2
 Title: Likelihood Based Inference for ARIMA Modeling
-Version: 3.0.3.9000
+Version: 3.0.4.9000
 Authors@R: 
     c(
     person("Jesse", 
diff --git a/NEWS.md b/NEWS.md
index 9642bcd..3450383 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,9 @@
 # arima2 (development version)
 
+# arima2 3.0.4
+
+* Added a check to ensure a random restart is considered an improvement only if it returns a model that has a proper variance matrix for estimated coefficients. 
+
 # arima2 3.0.3
 
 * Added `aicc` option to `aicTable`, and removed superfluous arguments. 
diff --git a/R/arima.R b/R/arima.R
index 5e6389e..bd4ae2d 100644
--- a/R/arima.R
+++ b/R/arima.R
@@ -542,7 +542,12 @@ arima <- function(x, order = c(0L, 0L, 0L),
           )  # End trycatch
         )
 
-        if (restart_result$error == 0 && restart_result$i_value + (eps_tol * 2) < best_value) {
+        # Make sure the best fit also has a proper covariant matrix for coefficients.
+        suppressWarnings(
+          inv_test <- !is.null(restart_result$i_var) && !any(is.nan(sqrt(diag(restart_result$i_var))))
+        )
+
+        if (restart_result$error == 0 && restart_result$i_value + (eps_tol * 2) < best_value && inv_test) {
           best_coef <- restart_result$i_coef
           best_res <- restart_result$i_res
           best_var <- restart_result$i_var