Re: Mathematica language issues

*To*: mathgroup at smc.vnet.net*Subject*: [mg53002] Re: Mathematica language issues*From*: Bill Rowe <readnewsciv at earthlink.net>*Date*: Sun, 19 Dec 2004 06:14:49 -0500 (EST)*Sender*: owner-wri-mathgroup at wolfram.com

On 12/18/04 at 3:59 AM, ruebenko at imtek.uni-freiburg.de (Oliver Ruebenkoenig) wrote: >Dear Maxim, >>All the typical issues with the Mathematica programming language >>are still present in version 5.1: >> Compile[{}, >> Module[{x = 0}, >> While[x++; EvenQ[x] ]; >> x >> ]][] >Compile[{}, Module[{x = 0}, x++; While[EvenQ[x]]; > x]][] >x++; EvenQ[x] is CompoundExpression[ x++, EvenQ[ x ] ] >While[ test ] needs a test not a CompoundExpression The usual syntax of While is While[test, expr] but While[test] is also allowed and test can be a compound expression. The issue is clearly related to how Mathematica evaluates the compound expression. Compile[{}, Module[{x = 0}, While[EvenQ[x], x++]; x]][] outputs 1 as expected Surprisingly, Compile[{}, Module[{x = 0}, While[x++, EvenQ[x]]; x]][] also outputs 1. I suspect if test becomes more complex, say a compound expression, deviating from the indicated syntax order won't continue to get the same result as using the expected order. Note, Compile[{}, Module[{x = 0}, While[x++; EvenQ[x]]; x]][] outputs 2 This indicates EvenQ[x] is being evaluated with the current value of x rather than the updated value resulting from x++. However, I still don't understand why Maxim's original code outputs 3. But I also don't see an issue. I am never surprised by unexpected output when I deviate from expected syntax. -- To reply via email subtract one hundred and four

**Follow-Ups**:**Re: Re: Mathematica language issues***From:*DrBob <drbob@bigfoot.com>