The function 



p(x) = 



exp -Or-*) 2 /2a 3 1 



where x is the mean and o~ is the standard deviation, is 

 illustrated in figure 1, 



-3-2-10 12 



AMPLITUDE IN STANDARD DEVIATION UNITS 



Figure 1 . Curve of the probability density fu no- 

 tion of a gaussian random variable (normalized to 

 a unit area under the curve). 



