code 35193; comment COMPUTATION OF NONEXPONENTIAL MODIFIED BESSEL FUNCTIONS OF FRACTIONAL ORDER; procedure NONEXP BESS IAPLUSN(A, X, N, IA); value A, X, N; real X, A; integer N; array IA; if X= 0 then begin IA[0]:= if A= 0 then 1 else 0; for N:= N step -1 until 1 do IA[N]:= 0 end else if A= 0 then begin NONEXP BESSI(X, N, IA) end else if A= .5 then begin real C; C:= .797 884 560 802 865 * SQRT(X); NONEXP SPHER BESSI(X, N, IA); for N:= N step -1 until 0 do IA[N]:= C * IA[N] end else begin integer M, NU; real R, S, LABDA, L, A2, X2; A2:= A+A; X2:= 2/X; L:=1; NU:= START(X,N,1) ; R:= S:= 0; for M:= 1 step 1 until NU do L:= L * (M+A2)/(M+1); for M:= NU step -1 until 1 do begin R:= 1/(X2 *(A+M)+R); L:= L*(M+1)/(M+A2); LABDA:= L*(M+A) * 2; S:= R * (LABDA + S); if M <= N then IA[M]:= R end; IA[0]:= R:= 1/(1+S)/GAMMA(1+A)/X2 **A; for M:= 1 step 1 until N do IA[M]:= R:= IA[M] * R; end; eop