Re: beginner question about syntax
- To: mathgroup at smc.vnet.net
- Subject: [mg109085] Re: beginner question about syntax
- From: "David Park" <djmpark at comcast.net>
- Date: Mon, 12 Apr 2010 22:59:06 -0400 (EDT)
Map maps the function onto to parts of the expression at Level 1, or at the levels you specify. But a is just a Symbol and has no Parts or Level 1. Therefore nothing happens. But the second expression does have parts at Level 1: a + b + c // FullForm Plus[a, b, c] So Map does operate on the items at Level 1, i.e., a, b and c. You could also write Map in shortcut form using "/@" to stand for Map, and #^2& to stand for the squaring Function: #^2 & /@ (a + b + c) a^2 + b^2 + c^2 David Park djmpark at comcast.net http://home.comcast.net/~djmpark/ From: AK [mailto:aaarbk at googlemail.com] Hi, 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 In[2]:=Map[Function[x, x^2], a + b + c] Out[2]:= a^2 + b^2 + c^2 If I enclose the second argument of Map[] inside a list, 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... thank you in advance.