Re: beginner question about syntax

*To*: mathgroup at smc.vnet.net*Subject*: [mg109111] Re: beginner question about syntax*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Mon, 12 Apr 2010 23:03:57 -0400 (EDT)

On 4/12/10 at 6:53 AM, aaarbk at googlemail.com (AK) wrote: >I'm a fairly seasoned user of another system who's just started >using Mathematica. Although at the moment I'm just playing around >with Mathematica (without any specific task at hand), trying to >figure out the Mathematica way of doing things from the >documentation (particularly the examples) there are some things I >can't seem to wrap my head around. For example, can anyone explain >the outputs for the inputs below: >In[1]:= Map[Function[x, x^2], a] >Out[1]:= a By default, Map works at level 1. A symbol with nothing assigned to it has no level 1. You could have gotten the output you were expecting by telling Map to work at level 0 which refers to the entire expression. That is: In[11]:= Map[Function[x, x^2], a, {0}] Out[11]= a^2 >In[2]:=Map[Function[x, x^2], a + b + c] >Out[2]:= a^2 + b^2 + c^2 This works since the expression a + b + c has a level 1. >If I enclose the second argument of Map[] inside a list, By doing that you create a level 1. >I get the expected output, but I don't understand what the operations >given in the example above represent and why the outputs are what they >are. Would appreciate an explanation for what's going here... For more detail see tutorial/LevelsInExpressions