' Many Digit Math for Integers  - quick test by vegipete
' Digits are stored in arrays
' The following uses base 1,000,000: this way, 6 decimal digits are stored in each element
'
' to do:
'   multiplication/division
'   decide how to represent negative numbers

bigsize = 16    ' (bigsize + 1) * 6 = number of digits
dim a(bigsize)
dim b(bigsize)
dim c(bigsize)

print "Fibonacci Numbers - each number is the sum of the previous 2. Fib0 = 0, Fib1 = 1."
a(0) = 0
b(0) = 1
do
 PrintLong c()
 AddLong a(),b(),c()
 CopyLong b(),a()
 CopyLong c(),b()
 do : loop until inkey$ <> ""
loop

'=======================================
sub AddLong x(),y(),z()
 local i,tmp,c=0
 for i = 0 to bigsize
   tmp = c + x(i) + y(i)
   z(i) = tmp MOD 1000000
   c = tmp \ 1000000
 next i
end sub

sub MultLong x(),y(),z()
 ' exercise left to the reader
end sub

sub CopyLong x(),y()
 local i
 for i = 0 to bigsize
   y(i) = x(i)
 next i
end sub

sub PrintLong x()
 local i,lead=0
 for i = bigsize to 0 step -1
   if x(i) or lead then
     print right$(string$(lead,"0")+str$(x(i)),6);
     lead = 6
   endif
 next i
 if not lead then print "0";
 print
end sub