function?[ApEn_valueCmrCmr_1]?=?fast_ApEn（signalr_factor）
%?Estimate?the?Aproximate?Entropy?（ApEn）?of?a?signal?using?a?fast?%?algorithm?for?the?ApEn?parameter?“m“?equal?to?2?
%?The?pattern?length?“m“?for?which?this?routine?was?implemented?is?2.?For?another?values?of?“m“?the?instructions?marked?with?a?（*）?in?the?end?must?be?changed.%?m=1?or?m=2
%?r?between?0.1*STD?and?0.25*STD?where?STD?is?the?signal?standard?deviation?%?N?（signal?length）?between?75?and?5000;
%?[ApEn_value]?=?fast_ApEn（signalr_factor）;%?Input?variables:%?signal?-?signal%?r_factor?-?factor?of?the?criterion?of?similarity??r_factor*std（signal）%?Output?variables:
%?ApEn_value?-?ApEn?calculated?from?the?signal
%?Optional?output?variables:%?C_m%?C_m_1
%?if?length（signal）<75?|?length（signal）>5000
%?slength=input（‘S