HP49-50G: help for recursive

[Gil]

True, and thanks, David.

But understanding new ways permits also to accept and learn from them and adopt them when we think that they are better than our initial answer/solution.

And, very often, HP Forum solutions are most inspiring for me — when simply reproduced or, better, understood.

Just as a remembrsnce, the basic idea is/was to reproduce, with a recursion on the HP50G, this following small recursive program from Albert Chan:

200 DEF FNL(X) ! = ln(1+X) - X, but more accurate
210 IF ABS(X)>=.4 THEN X=X/(SQRT(1+X)+1) @ FNL=FNL(X)*2-X*X @ GOTO 250
220 X2=X/(X+2) @ X4=X2*X2
230 X4=X4*(5005-X4*(5082-X4*969))/(15015-X4*(24255-X4*(11025-X4*1225)))
240 FNL=X2*(X4+X4-X)

F(.3) —>-3.76357355325E-2
F(2.) —> -.901387711332
F(100.) —> -95.3848794836

Regards,
Gil