From 0b2219f36c6a84f3585350e4e319685f9f4bab82 Mon Sep 17 00:00:00 2001
From: Thorsten Liebig <Thorsten.Liebig@gmx.de>
Date: Tue, 25 May 2010 12:26:04 +0200
Subject: [PATCH] matlab: transform TD-field data to frequency domain

---
 matlab/GetField_TD2FD.m | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 matlab/GetField_TD2FD.m

diff --git a/matlab/GetField_TD2FD.m b/matlab/GetField_TD2FD.m
new file mode 100644
index 0000000..b0638cf
--- /dev/null
+++ b/matlab/GetField_TD2FD.m
@@ -0,0 +1,33 @@
+function field_FD = GetField_TD2FD(field_TD, freq)
+% function field_FD = GetField_TD2FD(field_TD, freq)
+%
+% transform time-domain field data into frequency domain
+% 
+% example:
+%   freq = linspace(0,1e9,100); %target frequency vector
+%   field = ReadHDF5FieldData('tmp/Ht.h5');
+%   field_FD = GetField_TD2FD(field, freq);
+%
+% See also ReadHDF5FieldData
+%
+% openEMS matlab interface
+% -----------------------
+% author: Thorsten Liebig
+
+t = field_TD.time;
+
+field_FD.freq = freq;
+
+for nf = 1:numel(freq)
+    field_FD.values{nf} = 0;
+end
+    
+numTS = numel(field_TD.values);
+
+for n=1:numTS
+    for nf = 1:numel(freq)
+        f = freq(nf);
+        field_FD.values{nf} = field_FD.values{nf} + 2/numTS * field_TD.values{n}.*exp(-1i*2*pi*f*t(n));
+    end
+end
+