From 34e89bed4c9cebbca327a7375108d789e1fed7ee Mon Sep 17 00:00:00 2001
From: Evangelos Voyiatzis <evoyiatzis@gmail.com>
Date: Thu, 6 Feb 2025 17:23:40 +0200
Subject: [PATCH] implement extract in improper sqdistharm

---
 src/YAFF/improper_sqdistharm.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/YAFF/improper_sqdistharm.cpp b/src/YAFF/improper_sqdistharm.cpp
index f4beab3587..038063eae8 100644
--- a/src/YAFF/improper_sqdistharm.cpp
+++ b/src/YAFF/improper_sqdistharm.cpp
@@ -267,3 +267,15 @@ void ImproperSQDistHarm::read_restart(FILE *fp)
 
   for (int i = 1; i <= atom->nimpropertypes; i++) setflag[i] = 1;
 }
+
+/* ----------------------------------------------------------------------
+   return ptr to internal members upon request
+------------------------------------------------------------------------ */
+
+void *ImproperSQDistHarm::extract(const char *str, int &dim)
+{
+  dim = 1;
+  if (strcmp(str, "k") == 0) return (void *) k;
+  if (strcmp(str, "chi") == 0) return (void *) chi;
+  return nullptr;
+}