From f4d68f72d57d31743a3db3a4aa741e76b1034b9d Mon Sep 17 00:00:00 2001
From: Ali Gholami Rudi <ali@rudi.ir>
Date: Fri, 25 Jun 2021 01:38:16 +0430
Subject: [PATCH] box: handle zero ury in subscript correction

---
 box.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/box.c b/box.c
index 549912c..cc3bf72 100644
--- a/box.c
+++ b/box.c
@@ -297,7 +297,10 @@ void box_sub(struct box *box, struct box *sub, struct box *sup)
 	/* writing the subscript */
 	if (sub) {
 		/* subscript correction */
-		printf(".nr %s (%s+%s)*(%s-%s)/%s\n", nregname(sub_cor),
+		printf(".nr %s (%s-%s)\n", nregname(sub_cor),
+			nreg(box_wd), nreg(box_wdnoic));
+		printf(".if %s>0 .nr %s (%s+%s)*(%s-%s)/%s\n",
+			nreg(box_ht), nregname(sub_cor),
 			nreg(box_ht), nreg(sub_fall),
 			nreg(box_wd), nreg(box_wdnoic), nreg(box_ht));
 		printf(".nr %s -%s\n", nregname(sub_wd), nreg(sub_cor));
-- 
2.11.4.GIT