From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shriramana Sharma Subject: Double values - what precision do I use for fprintf? Date: Thu, 12 Jan 2006 18:00:19 +0530 Message-ID: <200601121800.19678.samjnaa@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline Sender: linux-c-programming-owner@vger.kernel.org List-Id: Content-Type: text/plain; charset="us-ascii" To: linux-c-programming@vger.kernel.org Please observe the following printf output of eighteen double variables: First I tried using "%20.15f" as the format string: 268.229220252114942 1.018511211250181 66.833038547989787 12.450505533056681 20.512170161382819 0.334923179252419 259.358845955701327 1.571934717666495 201.111247720862963 0.139476171219810 270.658029698352152 -0.612280599380678 105.175902698424665 -0.076345132989225 343.809699615507384 -0.219206370786681 Then I used "%30.25f": 268.2297152740335377529845573 1.0185111507334088098986058 66.8390907719954157073516399 12.4504269834231084956854829 20.5123328842112115921736404 0.3349264346316725426966343 259.3596100022817267927166540 1.5719383906021777708161835 201.1113154335791932680876926 0.1394751696317115263745734 270.6577319741974747557833325 -0.6122834912138217511312632 105.1758654981413201312534511 -0.0763454696609412730712307 343.8095929658045974974811543 -0.2192182978826520134418843 Ignoring the small differences in the two sets of data (longitude and speed of eight celestial bodies computer at two different instants) I wonder - if I keep increasing the number of decimal places where will it end? -- Shriramana Sharma http://samvit.org Running SUSE Linux 10.0 with KDE 3.5 -- Penguin #395953 resides at http://samvit.org subsisting on SUSE Linux 10.0 with KDE 3.5