Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2002
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2002

[Date Index] [Thread Index] [Author Index]

Search the Archive

Intersection[...,SameTest] ?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33054] Intersection[...,SameTest] ?
  • From: Konstantin L Kouptsov <klk206 at is5.nyu.edu>
  • Date: Wed, 27 Feb 2002 00:48:19 -0500 (EST)
  • Organization: New York University
  • Sender: owner-wri-mathgroup at wolfram.com

Intersection[..., SameTest->test] seem to do just that. However:

1. It is not clear from the manual (book or help browser), what this command
is supposed to return.

2. It simply does not work:

In[83]:=
a={1,2,3,4};
b={2,4,7,8};
Intersection[a,b,SameTest->(#1==2*#2&)]

Out[83]=
{1}

or more sophisticated:

In[85]:=
a={1,2,3,4};
b={2,4,7,8};
Intersection[a,b,SameTest->
	((Print[#1,"=?=",#2]||True) 
	&&#1==2*#2
	&&(Print[True]||True)&)
]

2 =?= 1
True
3 =?= 1
4 =?= 3
2 =?= 1
True
4 =?= 3
4 =?= 4

Out[85]=
{1}

which does not seem to enumerate all pairs.

What idea stands behind this function? what is supposed to do?

(well, for my task I sure could run double For[] cycle, but I am
curious about Intersection[])


  • Prev by Date: Large Files
  • Next by Date: which book is good to learn the programming in Mathematica?
  • Previous by thread: Large Files
  • Next by thread: which book is good to learn the programming in Mathematica?