function snr,p1,p2
sp1=size(p1)
sp2=size(p2)
if (sp1(1) ne sp2(1)) or (sp1(2) ne sp2(2)) then begin
  print,'Arrays not the same size in snr'
  return,0.
endif
tp1=total(float(p1)^2)
tp2=total((float(p2)-float(p1))^2)
s=fltarr(3)
; Compute the TUB SNR
s(0)=10.*alog10(tp1/tp2)
std=stdev(p1,mean)
error=float(p2)-float(p1)
rmse=stdev(error)
; Compute Marty's SNR
s(1)=mean/rmse
var=error(1:154,1:253)^2/((p1(1:154,1:253))/30.)
std=stdev(var,mean)
s(2)=mean
return,s
end