function?[Bspecwaxis]?=?bispecd?（y??nfft?wind?nsamp?overlap）
%BISPECD?Bispectrum?estimation?using?the?direct?（fft-based）?approach.
%	[Bspecwaxis]?=?bispecd?（y??nfft?wind?segsamp?overlap）
%	y????-?data?vector?or?time-series數據向量或時間序列
%	nfft?-?fft?length?[default?=?power?of?two?>?segsamp]
%	wind?-?window?specification?for?frequency-domain?smoothing窗口規范
%	???????if?‘wind‘?is?a?scalar?it?specifies?the?length?of?the?side
%	??????????of?the?square?for?the?Rao-Gabr?optimal?window??[default=5]
%	???????if?‘wind‘?is?a?vector?a?2D?window?will?be?calculated?via
%	??????????w2（ij）?=?wind（i）?*?wind（j）?*?wind（i+j）
%	???????if?‘wind‘?is?a?matrix?it?specifies?the?2-D?filter?directly
%	segsamp?-?samples?per?segment?[default:?such?that?we?have?8?segments]每段的樣本
%	????????-?if?y?is?a?matrix?segsamp?is?set?to?the?number?of?rows行數
%	overlap?-?percentage?overlap?[default?=?50]?重疊百分比
%	????????-?if?y?is?a?matrix?overlap?is?set?to?0.
%
%	Bspec???-?estimated?bispectrum:?an?nfft?x?nfft?array?with?origin
%	??????????at?the?center?and?axes?pointing?down?and?to?the?right.
%	waxis???-?vector?of?frequencies?associated?with?the?rows?and?columns
%	??????????of?Bspec;??sampling?frequency?is?assumed?to?be?1.

%??Copyright?（c）?1991-2001?by?United?Signals?&?Systems?Inc.
%???????$Revision:?1.8?$
%??A.?Swami???January?20?1993.

%?????RESTRICTED?RIGHTS?LEGEND
%?Use?duplication?or?disclosure?by?the?Government?is?subject?to
%?restrictions?as?set?forth?in?subparagraph?（c）?（1）?（ii）?of?the
%?Rights?in?Technical?Data?and?Computer?Software?clause?of?DFARS
%?252.227-7013.
%?Manufacturer:?United?Signals?&?Systems?Inc.?P.O.?Box?2374
%?Culver?City?California?90231.
%
%??This?material?may?be?reproduced?by?or?for?the?U.S.?Government?pursuant
%??to?the?copyright?license?under?the?clause?at?DFARS?252.227-7013.

%?---------------------?parameter?checks?-----------------------------

????[ly?nrecs]?=?size（y）;
????if?（ly?==?1）?y?=?y（:）;??ly?=?nrecs;?nrecs?=?1;?end

????if?（exist（‘nfft‘）?~=?1）????????????nfft?=?128;?end
????if?（exist（‘overlap‘）?~=?1）??????overlap?=?50;??end
????overlap?=?min（99max（overlap0））;
????if?（nrecs?>?1）??????????????????overlap?=??0;??end
????if?（exist（‘nsamp‘）?~=?1）??????????nsamp?=?0;???end
????if?（nrecs?>?1）????????????????????nsamp?=?ly;??end

????if?（nrecs?==?1?&?nsamp?<=?0）
???????nsamp?=?fix（ly/?（8?-?7?*?overlap/100））;
????end
????if?（nfft??
????overlap??=?fix（nsamp?*?overlap?/?100）;?????????????%?added?2/14
????nadvance?=?nsamp?-?overlap;
????nrecs????=?fix?（?（ly*nrecs?-?overlap）?/?nadvance）;


%?-------------------?create?the?2-D?window?-------------------------
??if?（exist（‘wind‘）?~=?1）?wind?=?5;?end
??[mn]?=?size（wind）;
??window?=?wind;
??if?（max（mn）?==?1）?????%?scalar:?wind?is?size?of?Rao-Gabr?window
?????winsize?=?wind;
?????if?（winsize?