Date: Wed, 13 Jan 2016 02:50:09 -0900 From: "CK" <nibbana@gmx.us> To: <freebsd-bugs@freebsd.org> Subject: dc(1) bugs Message-ID: <0M8edX-1ZxEjK1XcZ-00wE8S@mail.gmx.com>
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Original posting to freebsd-questions ... FreeBSD-9.3 dc(1) These appear to be bugs to me, but please verify if possible: ##### FIRST ##### $ dc -xe '50k16o16i.1vp' 0 $ dc -xe '50k10o16i.1vp' 0 $ dc -xe '50k10o10i.1vp' [0].31622776601683793319988935444327185337195551393252 This should be telling dc(1): a) scale is 50 (in decimal) digits. b) output in base16, base10, and base10 respectively. c) input will be in base16, base16, and base10 respectively. d) take the square root, and print it to the display. Of course, the 3rd example above is correct, but the first 2? Why 0? ###### SECOND ###### $ dc -xe '50k16o16i.4 2^p' [0].0A $ dc -xe '50k16o16i.0Avp' [0].2C572B0D5A1443EC508B9E24D8DF392750959EE138 This should be telling dc(1): a) scale is 50 (in decimal) digits. b) output in base16, input is now base16. c) square "0.4", and print it to the display (result=0.0A). d) take the square-root of "0.0A", and print it to the display. Of course, the square-root of a squared number should result in the orginal number. But, this is not happening. ##### THIRD ##### $ dc -xe '50k16o16i.4 2^p' [0].0A $ dc -xe '50k16o16i.40 2^p' [0].1000 $ dc -xe '50k16o16i.400 2^p' [0].10000 $ dc -xe '50k16o16i.4000 2^p' [0].1000000 dc(1) is supposed to be precise in the digits it calculates, but here? Something is not right about these results, or so it appears to me. ###### FOURTH ###### $ dc -xe '50k16o16i.1vp' 0 $ dc -xe '50k16o16i.10vp' [0].3EB4F9D9B6D094C33D38373D38777A7D9233A1B0FB $ dc -xe '50k16o16i.100vp' [0].3FBE55183CA5ADC8B39B27C6258E4C7E64338B909F $ dc -xe '50k16o16i.1000vp' [0].400000000000000000000000000000000000000000 Checking the result of the THIRD example, dc(1) is not outputting to the scale specified, and despite having all a scale of 50, they are all giving different results with inputs having a scale of only 1/2/3/4; Something seems broken to me. -- GNU's dc(1) is broken too: Wow! Great! Thanks! I really needed a calculator to do squares and square-roots of hexadecimal fractions, and I use FreeBSD, but their dc(1) is broken too ... http://lists.freebsd.org/pipermail/freebsd-questions/2016-January/269999.html http://lists.freebsd.org/pipermail/freebsd-bugs/2016-January/065825.html I was a little depressed in writing, sorry :) But I am so happy if I can find a working dc(1). Supposedly, it was the first utility, predating even UNIX. A modern computer should have a working calculator - at least, I think so. Thank you so much for your reply, I have some encryption-related software that depends on it. > On Tuesday 12 January 2016 23:05:41 CK wrote: > > > dc (GNU bc 1.06.95) 1.3.95 > > > > $ dc -e '50k16o16i.4vp' > > [0].727C9716FFB764D594A519C0252BE9AE6D00DC9192 > > > > This is not a 50-digit scale. > > It is a 50 digit scale base 10 which is of course shorter base 16. > > > $ dc -e '50k16o16i.727C9716FFB764D594A519C0252BE9AE6D00DC9192 2^p' > > [0].333333333333333333333333333333333325CC2DCA > > > > This is not even close to being the original number: 0.4. > > This appears to be true. I'll investigate why the algorithm is wrong. > > --Phil
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