970 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 as 0 In addition, three charts IX, X and XI are presented show- ing the functions § (8), ¢ (68) and 1e ® (8) dO in the three cases. The expressions for these functions are the following (1). Mode! Functions >(0) (0) [52 o(6) db 1 Exponential MWy=0 1 _ 8 0° © I .8 ne © 9 a il Mixed III Para-exponential m=1/2 W=1 46 8 2 eu (+25 a 6 4 — Se (A + B6) +6 Sk mê A+ 2 pol” 14,20]. with a A ss 90, (T-%7T,) (539-11) B___ © 27 0 (1-4 Y) C= L[r 30,4 ra YY Relations (251-2) for k=1, (251-3), (539-5), (539-6), (521-4) and 521-6). 1] Allais - pag. 274