NB. Evaluate charge exchange rates beta & beta' at temp. T
NB. assumes the existence of global tables cebbb & cebpp
Charge_Ex=: dyad define
'ni n'=. x   NB. number of elements and ions
t=. 1e_4* y
BCE=. BPCE=. (ni,n)$0

bb=. 2}."1 cebbb
bat=. (|: bb) betaf t          NB. Charge transfer rates at "t"
box_index=. <"(1) 2{."1 cebbb  NB. i,j indicies of ions, boxed
BCE=. bat  box_index} BCE      NB. insert into ion matrix

bp=. 2}."1 cebpp
bpat=. (|: bp) bplusf t
box_index=. <"(1) 2{."1 cebpp  NB. i,j indicies of ions, boxed
BPCE=. bpat  box_index} BPCE   NB. insert into ion matrix
BCE;BPCE
)

NB. These evaluate the fitting functions beta = a*t^b*(1 + c ^d*t), etc.
betaf=: dyad : '(0{x)*(y^(1{x))*(1+(2{x)*^((3{x)*y))' 
bplusf=: dyad : '(0{x)*(y^(1{x))*(1+(2{x)*^((3{x)*y))*(^-(4{x)%y)'