Re: Show doesn't work inside Do loop ?

*To*: mathgroup at smc.vnet.net*Subject*: [mg102013] Re: Show doesn't work inside Do loop ?*From*: AES <siegman at stanford.edu>*Date*: Sun, 26 Jul 2009 03:56:52 -0400 (EDT)*Organization*: Stanford University*References*: <32390795.1248259308283.JavaMail.root@n11> <h4951e$q2e$1@smc.vnet.net> <21621663.1248432817472.JavaMail.root@n11> <h4eeul$spv$1@smc.vnet.net>

In article <h4eeul$spv$1 at smc.vnet.net>, "David Park" <djmpark at comcast.net> wrote: (emphasis added) > > _On the other hand, Show does not generally generate a cell._ > > Of course, it is easier to just apply Print to the Show or Plot statements. > So it is possible to make Show generate output cells, but it _normally_ > doesn't do so. It normally only generates expressions, which because of its > special behavior a Do statement does not display. 1) Re your statements above: executing a single Input cell containing just Show[ Graphics[ Circle[ {0, 0}, 1] ] ] certainly generates an Output cell containing what looks like a "graphic" or "plot" to me. Is executing a cell containing a simple expression somehow an "abnormal" process or action? 2) On a more general note: Suppose you have an expression which contains an explicit symbol x , such that if you execute three consecutive cells containing x=1; expr x=2; expr x=3; expr or maybe expr/.x->1 expr/.x->2 expr/.x->3 you get three output cells containing three successive instances of expr (whatever that is) -- or appropriate error messages if executing expr one of those times has some side effect that messes up a subsequent execution. Would it not be reasonable to expect a cell containing Do[ expr, {x,1,3} ] to do _exactly_ the same thing? In other words, would it not be reasonable -- consistent -- sensible -- helpful -- the most useful -- to expect Do[ ] to be simply a "wrapper" that functioned in exactly that manner? I appreciate that Mathematica's Do[] apparently doesn't function that way -- or functions that way sometimes, based on mysterious criteria, but not other times; and suggest that this is not helpful or useful or consistent behavior for many users. Are there any fundamental reasons why a DoConsistently[ ] command could not be defined, such that DoConsistently[ expr, iterator ] would repeatedly put expr into a cell with each iterator instance applied to it, and churn out the sequential outputs? That, it seems to me, is what many users would want and expect.

**Follow-Ups**:**Re: Re: Show doesn't work inside Do loop ?***From:*Murray Eisenberg <murray@math.umass.edu>

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