From f21255ef1bddc548d303e8c67ce67142ff276b33 Mon Sep 17 00:00:00 2001
From: Holger Vogt <holger.vogt@uni-due.de>
Date: Tue, 22 Feb 2022 20:39:20 +0100
Subject: [PATCH] Fix regression bug #579 Accept numbers to ac statement in
 voltage (current) sources also given as parameters.

---
 src/frontend/inpcom.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/src/frontend/inpcom.c b/src/frontend/inpcom.c
index b720e5a4a..26ebb2047 100644
--- a/src/frontend/inpcom.c
+++ b/src/frontend/inpcom.c
@@ -9567,8 +9567,15 @@ static void inp_check_syntax(struct card *deck)
                 /* get first token after ac */
                 char* numtok = gettok_node(&nnacline);
                 char* numtokfree = numtok;
-                /* check if token is a valid number */
-                INPevaluate(&numtok, &err, 0);
+                /* Check if token is a parameter, to be filled in later */
+                if (*numtok == '\'' || *numtok == '{') {
+                    err = 0;
+                }
+                else {
+                    /* check if token is a valid number */
+                    INPevaluate(&numtok, &err, 0);
+                }
+
                 tfree(numtokfree);
             }
             /* if no number, replace 'ac' by 'ac 1 0' */