From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id 9D163138010 for ; Wed, 5 Sep 2012 12:47:23 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id F252F21C01F; Wed, 5 Sep 2012 12:47:03 +0000 (UTC) Received: from mail-bk0-f53.google.com (mail-bk0-f53.google.com [209.85.214.53]) by pigeon.gentoo.org (Postfix) with ESMTP id 5FB5FE0783 for ; Wed, 5 Sep 2012 12:46:14 +0000 (UTC) Received: by bkwj4 with SMTP id j4so236696bkw.40 for ; Wed, 05 Sep 2012 05:46:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; bh=gDcn9Wv293a8y+qedzjuI6wW9MEFOTa7R2q2e6JFdU4=; b=eX/LvCjl16KwHPC/9jLfYj2v8hDlwSTgn01Lb+ehyd5xZlERPO0X8InM+xBI540LgW JjRsU8Q8WhicMxm0ElQhTDref5Vk8Per61xgiUE9o3Q+dc7+iOAIdEYKaslCqDpOMWy6 52GIZsmXlY9sYjkLXKB55Joq+98GWP9mtbnCea8Q+nDYPWWaQzrA0IvSMvgV9IOkT4PV TmrQ9ynDZ0KX7sV7M0yJrxBRCMwE8grm681twfI+1NaUIFYX/y9I77xzlzBerev7MWLz QI/1bDmGksTd4eGFzqRDz9bnnpKAvfzh9zN1+uYJ74hahgw7qERYFKRYw0q5qV9Mb+5J WWwg== Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-dev@lists.gentoo.org Reply-to: gentoo-dev@lists.gentoo.org MIME-Version: 1.0 Received: by 10.204.155.146 with SMTP id s18mr9272943bkw.23.1346849173479; Wed, 05 Sep 2012 05:46:13 -0700 (PDT) Sender: freemanrich@gmail.com Received: by 10.205.65.136 with HTTP; Wed, 5 Sep 2012 05:46:13 -0700 (PDT) In-Reply-To: <20120905122725.15d16d77@googlemail.com> References: <50411874.4060204@gentoo.org> <20120831214611.088b3f50@googlemail.com> <50469795.2070901@gentoo.org> <20120905122725.15d16d77@googlemail.com> Date: Wed, 5 Sep 2012 08:46:13 -0400 X-Google-Sender-Auth: VRtRWAi5s2dig7cZK3s30vkgNUo Message-ID: Subject: Re: [gentoo-dev] HDEPEND (host dependencies for cross-compilation) for EAPI 5? From: Rich Freeman To: gentoo-dev@lists.gentoo.org Content-Type: text/plain; charset=ISO-8859-1 X-Archives-Salt: d026d668-f7ce-4e75-8e4c-8ad6d94e947e X-Archives-Hash: 65371c436059440daa0ad69f31c65416 On Wed, Sep 5, 2012 at 7:27 AM, Ciaran McCreesh wrote: > Uhm. O(n) == O(n/2). Anything assuming they're different is just wrong. We're basically debating definitions. O notation is used to indicate how algorithms scale and nobody uses O(n/2) and such as a result. An algorithm that is twice as slow is still twice as slow. That might or might not matter. However, this isn't the domain where O notation is used. You use O notation when your algorithm takes 30 seconds to run and you want to know what happens with the dataset doubles 3000 times. It generally doesn't matter if the result is that it will take 1 trillion years to operate or 2 trillion years. You care more about whether it will take minutes, hours, weeks, years, or whatever. I can't really think of any practical examples where multiplying the time to parse a list of maybe 50 items vs 5 lists of 10 items is going to make that big of a difference. They're just lines in a text file - your CPU can compare a few billions characters per second. Sure, if you add 75 layers of abstraction you might be able to find just the right point where a factor of 5 is going to make it intolerable but a factor of 1 is almost acceptable, but go ahead and add/remove a few layers and suddenly it is all fine or all horrible anyway. That is a bit contrived. That's why everybody ignores constant factors in O notation anyway. Rich