Re: Function returns null
- To: mathgroup at smc.vnet.net
- Subject: [mg104728] Re: [mg104689] Function returns null
- From: Bob Hanlon <hanlonr at cox.net>
- Date: Sun, 8 Nov 2009 06:45:38 -0500 (EST)
- Reply-to: hanlonr at cox.net
If the last thing inside your module is a semi-colon you will get Null.
However, you might use
sOd[x0_] :=
Total[IntegerDigits[IntegerPart[x0]]]
sOd[3329]
17
Bob Hanlon
---- Michael Greene <mgreene at csumb.edu> wrote:
=============
I'm getting an unexpected result when I remove a print statement from my
function. The function computes a single digit sum of digits and returns
what I expect as long as the print statement just prior to the function exit
is present. I can verify that by invoking the function within a print
statement, e.g.,
Print["sOd returned - ",sOd[3329]]
When I remove the print within the function, the function returns a null
result. What simple point am I missing ? Does the := operator have something
to do with this?
Here is the function: (with embedded print statement)
sOd[x0_] := Module[{sodv, x, digit},
x = IntegerPart[x0]; (* ensure we have an integer input*)
sodv = x;
If[(x > 9), { (* sum digits if input has two or more digits*)
sodv = 0;
While[x > 0,
digit = (FractionalPart[x /10])*10;
sodv = sodv + digit;
x = IntegerPart[x/10];
];
sodv = sOd[sodv]; (* check for multiple digit sum *)
}
]
Print["sOd returns -", sodv]; (* remove this and function returns null*)
Return[sodv]; (* return single digit sum *)
]
Thanks,
Michael Greene