diff --git a/SimPkg_F21(student_ver)/xenia_nonlinearopt.m b/SimPkg_F21(student_ver)/xenia_nonlinearopt.m
index 96a3182..56d03ca 100644
--- a/SimPkg_F21(student_ver)/xenia_nonlinearopt.m
+++ b/SimPkg_F21(student_ver)/xenia_nonlinearopt.m
@@ -232,7 +232,7 @@ function [lb, ub] = bounds(start_idx, end_idx)
         
     end
 
-    for i=1:start_idx:end_idx
+    for i=start_idx:end_idx
         ub=[ub;ub_u];
         lb=[lb;lb_u];
     end