HP49-50G: help for recursive

[Albert Chan]

Hi, Gil

I am unclear which of your code (FNL, FNL2, FNL4) work.
Some examples would be nice.

Ignore the fact that FNL(X) does not need recursion (see previous post)
Ignore also global variables should really be local, as SUB program.

Here is how we simulate recursions for machine that does not support it, with a stack.

200 DIM S(99) @ DEF FNL(X) ! = ln(1+X) - X, but more accurate
210 FOR I=1 TO 99 @ IF ABS(X)<.4 THEN 230
220 X=X/(SQRT(1+X)+1) @ S(I)=X @ NEXT I ! fill stack
230 X2=X/(X+2) @ X4=X2*X2
240 X4=X4*(5005-X4*(5082-X4*969))/(15015-X4*(24255-X4*(11025-X4*1225)))
250 L=X2*(X4+X4-X)
260 WHILE I>1 @ I=I-1 @ X=S(I) @ L=L+L-X*X @ END WHILE ! undo stack
270 FNL=L @ END DEF

Again, this is for illustration only.
We don't want recursions (with rounding errors) when it is not needed.