Recursive programs in XCAS.

[John P]

(02-12-2017 01:41 AM)Han Wrote:  Can you provide a bit more information on what you have tried? Perhaps a snippet of code might provide a better idea of what you are trying to achieve. Or even a better description of what you wan to do beyond a generic description of "recursive program."

Fibonnaci example

Code:


fibon(n):=
begin
  if (n == 1) then return(1); end;
  if (n == 2) then return(1); end;
  if (n > 2) then
    return( fibon(n-1) + fibon(n-2) );  
  end;
end;

In general, any CAS code on the HP Prime should port as easily as copy/paste -- WITH EXCEPTIONS FOR A FEW COMMANDS (e.g. idenmat() on xcas is identity() )

Actually, I am trying to port the program, that you provided some time ago for HP Prime, to the PocketCAS on my iPhone 6+. On the HP Prime it works great, but on the iPhone 6+ I can't get it to work. Below I paste your original prgm. for the computation of the set of combinations from the set (list).

EXPORT COMBOSET(s,n)
BEGIN
local l:={};
local sl:={};
local tl:={};
local i,j;
local m:=size(s);

case
if n==m then l:={s}; end;
if n==1 then l:=makelist({s(X)},X,1,m); end;
if n>m then l:={}; end;
for i from 2 to m-n+2 do
sl:=sub(s,i,m);
tl:=COMBOSET(sl,n-1);
for j from 1 to size(tl) do
tl(j):=concat({s(i-1)},tl(j));
end;
l:=concat(l,tl);
end;
end;

return(l);

END;