diff --git a/eeg_rpsd.m b/eeg_rpsd.m
index 7d21d00..96a467e 100644
--- a/eeg_rpsd.m
+++ b/eeg_rpsd.m
@@ -1,14 +1,26 @@
 function psdmed = eeg_rpsd(EEG, nfreqs, pct_data)
 
+
+% Validate EEG input
+if ~isstruct(EEG) || ~isfield(EEG, 'icaweights') || ~isfield(EEG, 'icaact') || ...
+   ~isfield(EEG, 'srate') || ~isfield(EEG, 'pnts') || ~isfield(EEG, 'trials')
+    error('EEG must be a struct with fields: icaweights, icaact, srate, pnts, trials');
+end
+
 % clean input cutoff freq
 nyquist = floor(EEG.srate / 2);
 if ~exist('nfreqs', 'var') || isempty(nfreqs)
     nfreqs = nyquist;
+elseif ~isnumeric(nfreqs) || nfreqs <= 0 || floor(nfreqs) ~= nfreqs
+    error('nfreqs must be a positive integer');
+    
 elseif nfreqs > nyquist
     nfreqs = nyquist;
 end
 if ~exist('pct_data', 'var') || isempty(pct_data)
     pct_data = 100;
+elseif ~isnumeric(pct_data) || pct_data <= 0 || pct_data > 100
+    error('pct_data must be a number between 0 and 100');
 end
 
 % setup constants
@@ -23,15 +35,13 @@
 cutoff = floor(EEG.pnts / n_points) * n_points;
 index = bsxfun(@plus, ceil(0:n_points / 2:cutoff - n_points), (1:n_points)');
 if ~exist('OCTAVE_VERSION', 'builtin')
-    rng('default')
+    rng('shuffle')
 else
-    rand('state', 0);
+    rand('seed', sum(100 * clock));
 end
 n_seg = size(index, 2) * EEG.trials;
 subset = randperm(n_seg, ceil(n_seg * pct_data / 100)); % need to improve this
-if exist('OCTAVE_VERSION', 'builtin') == 0
-    rng('shuffle')
-end
+
 
 % calculate windowed spectrums
 psdmed = zeros(ncomp, nfreqs);