From a2508fef13f817f29f3482b96ea232cb2d2e04e7 Mon Sep 17 00:00:00 2001
From: Evangelos Voyiatzis <evoyiatzis@gmail.com>
Date: Thu, 6 Feb 2025 15:41:20 +0200
Subject: [PATCH] implement extract in improper harmonic

---
 src/MOLECULE/improper_harmonic.cpp | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/MOLECULE/improper_harmonic.cpp b/src/MOLECULE/improper_harmonic.cpp
index 06647fb93b..b9fda62343 100644
--- a/src/MOLECULE/improper_harmonic.cpp
+++ b/src/MOLECULE/improper_harmonic.cpp
@@ -276,3 +276,15 @@ void ImproperHarmonic::write_data(FILE *fp)
   for (int i = 1; i <= atom->nimpropertypes; i++)
     fprintf(fp, "%d %g %g\n", i, k[i], RAD2DEG * chi[i]);
 }
+
+/* ----------------------------------------------------------------------
+   return ptr to internal members upon request
+------------------------------------------------------------------------ */
+
+void *ImproperHarmonic::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;
+}