function?[snr_value?shift]?=?snr（signalsignal_plus_noisemax_shiftshowplot）

%?[snr_value?shift]?=?snr（signalsignal_plus_noise?max_shiftshowplot）?returns?the
%?signal-to-noise?ratio?computed?from?the?input?signals.?|Max_shift|?gives
%?the?maximum?time-shift?（in?samples）?between?signal?and?signal_plus_noise.
%?The?actual?time-shift?（obtained?from?the?maximum?of?the?cross-correlation
%?and?returned?as?|shift|）?is?taken?into?account?to?estimate?the?noise.?If
%?signal?are?of?different?length?the?shortest?length?is?used.
%?If?|showplot|?is?specified?then?the?signal?signal_plus_noise?and?error?
%?are?plotted?and?the?SNR?is?printed?on?the?plot.
%?
%?T?DUTOIT?13:49?12/03/2007


sig_length=min（length（signal）length（signal_plus_noise））;
sig_length=floor（sig_length/2）*2;?%?make?it?even
signal=signal（1:sig_length）;?
signal_plus_noise=signal_plus_noise（1:sig_length）;

len=min（[max（10*max_shift1000）?sig_length-1]）;
ha