Path: csiph.com!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: rbowman Newsgroups: comp.os.linux.misc Subject: Re: [OT] Dead DEC Punch card times (was Re: Taking Speedy too seriously) Date: 8 Nov 2026 18:52:33 GMT Lines: 22 Message-ID: References: <18dee4b6cab427fa$865$2574533$802601b3@news.usenetexpress.com> <11c8mg3$2e89e$2@kst.eternal-september.org> <_ZucnafJTvBFc3r3nZ2dnZfqnPGdnZ2d@giganews.com> <11c8rq9$1e6t$1@gal.iecc.com> <11c9ibo$2e740$1@dont-email.me> <11c9rph$2oln7$7@dont-email.me> <11ce4vn$85p2$2@dont-email.me> <11cg959$12d33$4@dont-email.me> <11cirgn$1votj$8@dont-email.me> <11cjsfa$29mft$1@dont-email.me> <11cn316$3bnof$15@dont-email.me> <11cnd3l$3gjc4$1@dont-email.me> <11co6km$3r41p$2@dont-email.me> <11cpsg8$b2v5$1@dont-email.me> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Trace: individual.net 2xAV4sy+CLDiYoxV1x0qSACefX5qdiTcCK5X/0lMasgom/uGTE Cancel-Lock: sha1:S3aozpmzMCeQkWK2pRtfay/s7rk= sha256:NQzIbkF7M5sNPBPcyHnb5G0WxqJengIgj9kz+Y+Cn3s= User-Agent: Pan/0.165 (Kostiantynivka) Xref: csiph.com comp.os.linux.misc:95355 On Sun, 8 Nov 2026 05:12:38 -0800, Lars Poulsen wrote: > After 60 years of programming, I did not know it was in the library. I > always just did > h = sqrt(x*x+y*y); > but if he did not use -lm, did he do his own sqrt() too? And was this on > a machine without hardware floating point? I can't remember exactly what the problem was but he made an assumption that didn't require finding a hypotenuse. It worked well enough that nobody noticed. iirc it had to do with alerts. The clients could add specific points to the system, a hazardous storage location, for example and set a radius for the trigger. If an incident was reported at point A, any of the alerts within N feet should pop up. The client reported an alert was within the configured N feet but didn't show up and provided a screen shot of a map in Arc Desktop. It was very close but no cigar. As I think about it I believe the simplification was creating a bounding box rather than a circle with the radius of N to avoid doing the math.