wolfram-mathematica

Definition "knows" the way how a value for a symbol was defined: using Set or SetDelayed . But how? As I understand, after a value for a symbol was assigned there is no any difference for the evaluator how it was assigned: by using Set or SetDelayed . It can be illustrated by the function OwnValues which always returns definitions with the Head RuleDelayed . How Definiton obtains this information? In[1]:= a=5;b:=5; Definition[a] Definition[b] OwnValues[a] Out[2]= a=5 Out[3]= b:=5 Out[4]= {HoldPattern[a]:>5} Alexey Popkov OwnValues[a] = {HoldPattern[a] -> 3}; OwnValues[a] gives {HoldPattern[a]

The function MapAll was seen as important enough to warrant the short form //@ , yet I rarely use it, especially compared to others like /@ , /. and @@@ which I use almost everywhere. What applications best leverage MapAll ? Is it used mostly in certain fields or programming styles? How often can it be used compared to other operators? //@ is a "post-order tree traversal". It visits every node in a tree structure, each node's children being visited before the node itself. The supplied function is called with each node as its argument, the node's children already having been "expanded" by a

In current version of Mathematica these keyboard shortcuts are quite handy Ctrl+K completes current command GraphPl -> press Ctrl+K -> GraphPlot Ctrl+Shift+K completes current command and adds argument placeholders which could be replaced with actual values with tab key GraphPl -> press Ctrl+Shift+K -> GraphPlot[{vi1->vj1,vi2->vj2,...}] However I couldn't find any keyboard option to show associated settings/options For instance Say If I need to plot a graph with different layouts, I know I need to set Method with one of these Possible settings "CircularEmbedding" "RandomEmbedding"

I was under the impression that = is an assignment, == is a numeric comparison, and === is a symbolic comparison (as well as in some other languages == being equal to and === being identical to . However, looking at the following it would appear that this is not necessarily the case... In: x == x Out: True In: x === x Out: True In: 5 == 5 Out: True In: 5 === 5 Out: True In: x = 5 Out: 5 In: 5 == x Out: True In: 5 === x Out: True In: 5 5 == 5x Out: True In: 5 5 === 5x Out: True In: x == y Out: x == y In: x === y Out: False In: y = x Out: 5 In: x == y Out: True In: x === y Out: True So what

Is there a way to start up a mathematica front end (GUI) from a (Windows) command prompt and have it eval a notebook without further user action? even though mathematica.exe takes the -run and -initfile options they dont work the same as they do with math.exe. (-run ''<<file.m'' wants to open a file named ''<<file.m'' for example) Thanks. The first answer looks promising, however I get FrontEndObject::notavail A front end is not available (per docs it is "UseFrontEnd" by the way.) Perhaps a path issue, however even after setting $FrontEndLaunchCommand no joy.. Re: Initialization Cell -- that

I'm running a Table function which will take too much time to complete. I wanted to know if there's a way to retrieve the results computed so far. Leonid Shifrin The proposed solution Here is a version of Table that is Abort -able and will keep the intermediate results collected so far. It is a modified version of the solution posted here . ClearAll[abortableTable]; SetAttributes[abortableTable, HoldAll]; abortableTable[expr_, iter__List] := Module[{indices, indexedRes, sowTag}, SetDelayed @@ Prepend[Thread[Map[Take[#, 1] &, List @@ Hold @@@ Hold[iter]], Hold], indices]; indexedRes = If[# ===