From ad9e32ea98a5500790fd1ebb8e8b1617aa6e175e Mon Sep 17 00:00:00 2001
From: Jiri Pittner <jiri@pittnerovi.com>
Date: Fri, 8 Jul 2022 11:36:04 +0200
Subject: [PATCH] expi(A) = exp(i A) function

---
 matexp.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/matexp.h b/matexp.h
index 100da1c..3e0bcc8 100644
--- a/matexp.h
+++ b/matexp.h
@@ -379,6 +379,15 @@ for(int i=0; i<power; i++)
 	}
 }
 
+//exp(iA)
+template<class T>
+NRMat<std::complex<T> > expi(const NRMat<T> &x)
+{
+NRMat<T> r,i;
+sincos(i,r,x);
+return complexify(r,i);
+}
+
 
 
 //this simple implementation seems not to be numerically stable enough