From 24da3f673b12ebad30895374bbd71c04f472eb9f Mon Sep 17 00:00:00 2001
From: Jan Petykiewicz <jan@mpxd.net>
Date: Tue, 23 May 2023 13:07:26 -0700
Subject: [PATCH] eigness is positive

---
 meanas/fdfd/bloch.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meanas/fdfd/bloch.py b/meanas/fdfd/bloch.py
index 9dacdee..800a603 100644
--- a/meanas/fdfd/bloch.py
+++ b/meanas/fdfd/bloch.py
@@ -754,7 +754,7 @@ def eigsolve(
         Av = (scipy_op @ v.copy())[:, 0]
         eigness = norm(Av - (v.conj() @ Av) * v)
         f = numpy.sqrt(-numpy.real(n))
-        df = numpy.sqrt(-numpy.real(n + eigness))
+        df = numpy.sqrt(-numpy.real(n) + eigness)
         neff_err = kmag * (1 / df - 1 / f)
         logger.info(f'eigness {i}: {eigness}\n neff_err: {neff_err}')