From 28a53cf5e8dc712d51a4272d262533b8ce1f4572 Mon Sep 17 00:00:00 2001
From: Chang-SHAO <101379630+Chang-SHAO@users.noreply.github.com>
Date: Thu, 4 Jul 2024 00:52:07 +0800
Subject: [PATCH] Update powell.py

---
 pypop7/optimizers/ds/powell.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/pypop7/optimizers/ds/powell.py b/pypop7/optimizers/ds/powell.py
index 0b821ec72..0c584c7d2 100644
--- a/pypop7/optimizers/ds/powell.py
+++ b/pypop7/optimizers/ds/powell.py
@@ -85,6 +85,9 @@ def _minimize_scalar_bounded(func, bounds,
 def _line_for_search(x0, alpha, lb, ub):
     # this is adopted from https://github.com/scipy/scipy/blob/main/scipy/optimize/_optimize.py
     nonzero, = alpha.nonzero()
+    if len(nonzero) == 0:
+        return (0, 0)
+      
     lb, ub = lb[nonzero], ub[nonzero]
     x0, alpha = x0[nonzero], alpha[nonzero]
     low, high = (lb - x0)/alpha, (ub - x0)/alpha