public inbox for gcc-prs@sourceware.org help / color / mirror / Atom feed
From: "Peter J. Stieber" <pete@toyon.com> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org Subject: Re: libstdc++/3181: Unable to use sqrt,cos,sin,... with int argument. Date: Wed, 20 Jun 2001 09:26:00 -0000 [thread overview] Message-ID: <20010620162603.1225.qmail@sourceware.cygnus.com> (raw) The following reply was made to PR libstdc++/3181; it has been noted by GNATS. From: "Peter J. Stieber" <pete@toyon.com> To: <bkoz@gcc.gnu.org>, <nobody@gcc.gnu.org>, <gcc-prs@gcc.gnu.org>, <gcc-bugs@gcc.gnu.org> Cc: <gcc-gnats@gcc.gnu.org> Subject: Re: libstdc++/3181: Unable to use sqrt,cos,sin,... with int argument. Date: Wed, 20 Jun 2001 09:16:12 -0700 The book by Nicolai Josuttis "The C++ Standard Library - A Tutorial and Reference" has a good discussion of this topic (pp.581-582 in my copy). The fact that standard conforming behavior is defined as overloading the functions for all floating-point types (float, double and long double) leads to this problem. In the old days, non-standard function names were used (sqrtf, sqrtl, cosf, cosl,...) for the other floating point types, so implicit conversion would work. It is common in numeric programming (although not good practice) to see code like: double Pi = acos(-1); This will now cause problems, but it's always nice to work with legacy code. Since the old standard function names were defined for double FunctionName(double), you could overload for all numeric types and cast: namespace std { double sqrt(int a) { return sqrt(static_cast<double>(a)); } double sqrt(long a) { return sqrt(static_cast<double>(a)); } . . . }; This behavior could be controlled by compiler switches or using the preprocessor. The work-around I use in my code is to make the following changes acos(-1) change to acos(-1.0) or int i; acos(i) changes to acos(static_cast<double>(i)) but for large projects, this would be a pain.
next reply other threads:[~2001-06-20 9:26 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2001-06-20 9:26 Peter J. Stieber [this message] -- strict thread matches above, loose matches on Subject: below -- 2003-05-11 9:16 gdr 2002-11-06 14:46 Phil Edwards 2002-11-06 10:29 bangerth 2002-11-06 10:16 Gabriel Dos Reis 2002-11-06 10:06 Gabriel Dos Reis 2002-11-06 9:36 Gabriel Dos Reis 2002-11-06 9:36 Wolfgang Bangerth 2002-11-06 9:35 bangerth 2002-11-06 9:26 Wolfgang Bangerth 2002-11-06 9:16 Wolfgang Bangerth 2002-04-19 12:46 Phil Edwards 2001-06-13 19:43 bkoz 2001-06-13 16:46 pete
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20010620162603.1225.qmail@sourceware.cygnus.com \ --to=pete@toyon.com \ --cc=gcc-prs@gcc.gnu.org \ --cc=nobody@gcc.gnu.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).