Solved

How to remove negative numbers from a list in Prolog

Posted on 2008-10-07
3
1,158 Views
Last Modified: 2011-10-03
I'm trying to take a list, and remove only the negative numbers. So far i have this

non_neg([],[]).
non_neg([H|T],S) :- H<0, non_neg(T,S).
non_neg([H|T],S) :- H>=0, non_neg(T,H).

I'm pretty sure the error is in the 3rd line because when i query with an empty list or a list consisting of only negaive numbers it works fine. Sorry i'm a noob.
0
Comment
Question by:toymachiner62
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
3 Comments
 
LVL 84

Expert Comment

by:ozo
ID: 22666117
What is the second arg of non_neg?
0
 
LVL 2

Author Comment

by:toymachiner62
ID: 22666406
The list after the negative number has been removed
0
 
LVL 84

Accepted Solution

by:
ozo earned 125 total points
ID: 22666466
In that case, shouldn't
non_neg([H|T],S) :- H>=0, non_neg(T,H).
be
non_neg([H|T],S) :- H>=0, non_neg(T,[H|S]).
0

Featured Post

Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
ejb stateless example 2 68
how i declare an array which contains email address corresponding to names. 2 83
programming a polycom voip phone 3 86
Ruby or Python 7 133
Since upgrading to Office 2013 or higher installing the Smart Indenter addin will fail. This article will explain how to install it so it will work regardless of the Office version installed.
Computer science students often experience many of the same frustrations when going through their engineering courses. This article presents seven tips I found useful when completing a bachelors and masters degree in computing which I believe may he…
In this fifth video of the Xpdf series, we discuss and demonstrate the PDFdetach utility, which is able to list and, more importantly, extract attachments that are embedded in PDF files. It does this via a command line interface, making it suitable …

751 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question