I am trying a simple recursion but without success. I always get the error of the function not being defined in numeric mode and just the first recursion step in symbolics. What am I doing wrong?

In the meantime I found a workarund but I am not sure if its intended to work that way. I add a line (]) and the I delete one of the two placeholders created (the vertical line will still be there) and then I type the function body in the remaining placeholder.

The failing of the symbolic evaluation with parameter n (even when using the sum symbol) is not a bug, I guess, but just a limitation of the symbolics implemented so far. But the error message should be a different one with symbolic eval, as n not being defined is not an error with symbolics. Guess it would be best if the expressions would simplify to themselves if SMath fails with a simplification (f(n) --> f(n)) without an error.

P.S.: I am not an experienced user of SMath at all, but may I suggest we can get back the right arrow for symbolic evaluations (maybe customizeable as in Mathcad). I know they where there in former SMath versions and still are in the online Live version.
Just noticed that I am not able to type simple parenthesis in the Live-version (annoying), but I don't know if that ever was possible - I seldom used it.

Edited by user 25 August 2013 21:14:19(UTC)  | Reason: Not specified

Thanks for the quick answer. Any logic behind this behaviour? I don't need that line add and delete placeholder with non-recursive functions.


Agreed, concerning the recursive function, as we don't have a way to tell SMath that we want n to be a positive integer (BTW, the assume modifier in Mathcad as so often doesn't work in this case either). But concerning the sum operator SMath could know the result (as does Mathcad) because there should be an implicit assumption of n being an integer.

Thanks for the reply.

Edited by user 24 August 2013 22:18:55(UTC)  | Reason: Not specified

If you replace if() by boolean expressions, then symbolic or numeric evaluation will crash smath. This is possibly due to lack of recursion stopping.

Edited by user 25 August 2013 00:36:49(UTC)  | Reason: Not specified

Thats a pity. It would be very useful to be able to have an optical different appearence of the two methods of evaluation. I am not sure but it would look to me that it should not be that much effort to (re)implement that.

I wouldn't had expected that function to work either but as I already wrote in my reply to Martin it could with a slight modification if SMath had implemented shortcut evaluation.


As have Mathcad's symbolics ;-)

While searching the forum for recursion some hours ago I stumbled over a posting where somebody posted an example which crashes SMath and somebody else answered that in a new version (old from todays point of view) this will not be the case anymore. I tried the example and it crashes the current (stable) version of SMath. I tried to find that thread to reference it here, but it looks like searching the forum does not work at the moment. Anybody with some more information what happened to recursion over the time of program development? Obviously an improvement was taken back for some reason.

Regards

EDIT: I found the thread I mentioned above (using the internal search - the custom google search still is broken for me). It looks like infinite recursions did not crash versions 0.89 and 0.90 while they do crash the current version 0.96 (and did with version prior to 0.89).
http://en.smath.info/forum/yaf_postst1085_bad-recursive-function-calling-causes-crash.aspx

Edited by user 25 August 2013 12:46:36(UTC)  | Reason: Not specified