rest_nextpow2_one35.m
22f22bf83060master

rest_nextpow2_one35.m
View Options

			function Result = rest_nextpow2_one35(n)
			%Compute the min length for FFT according to AFNI's algorithm, By Xiao-Wei Song
			%------------------------------------------------------------------------------------------------------------------------------
			% Copyright(c) 2007~2010
			% State Key Laboratory of Cognitive Neuroscience and Learning in Beijing Normal University
			% Written by Xiao-Wei Song
			% http://resting-fmri.sourceforge.net
			% <a href="Dawnwei.Song@gmail.com">Mail to Author</a>: Xiaowei Song
			% Version=1.0;
			% Release=20070903;

			if length(n)>1
			n = cast(length(n),class(n));
			end
			if n<16
			Result =2^nextpow2(n);
			return;
			end

			limit =nextpow2(n); %n=134, limit=8
			tbl=[2^(limit-1):2^limit]; %tbl =128, 129, ... , 256
			tbl =tbl(find(tbl>=n)); %tbl =134, 135, ... , 256
			for x=1:length(tbl)
			Result =tbl(x);
			[f,p]=log2(Result);
			if ~isempty(f) & f == 0.5 %Copy from nextpow2.m
			return;
			end
			if mod(Result,3*5)==0
			y= Result /(3*5);
			[f,p]=log2(y);
			if ~isempty(f) & f == 0.5 %Copy from nextpow2.m
			return;
			end
			end
			if mod(Result,3)==0
			y= Result /3;
			[f,p]=log2(y);
			if ~isempty(f) & f == 0.5 %Copy from nextpow2.m
			return;
			end
			end
			if mod(Result,5)==0
			y= Result /5;
			[f,p]=log2(y);
			if ~isempty(f) & f == 0.5 %Copy from nextpow2.m
			return;
			end
			end
			end
			Result =NaN; % Should not reach, except when n=1

			% csfft_nextup35 in AFNI list 1~1024, 20070516, dawnsong
			% 2
			% 4
			% 6
			% 8
			% 10
			% 12
			% 16
			% 20
			% 24
			% 30
			% 32
			% 40
			% 48
			% 60
			% 64
			% 80
			% 96
			% 120
			% 128
			% 160
			% 192
			% 240
			% 256
			% 320
			% 384
			% 480
			% 512
			% 640
			% 768
			% 960
			% 1024