Re: 34.123*89 = 3036.95 (3036.947)
- To: mathgroup at smc.vnet.net
- Subject: [mg47916] Re: 34.123*89 = 3036.95 (3036.947)
- From: "Christopher J. Henrich" <chenrich at monmouth.com>
- Date: Fri, 30 Apr 2004 19:26:54 -0400 (EDT)
- References: <c6s538$pkf$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
In article <c6s538$pkf$1 at smc.vnet.net>, Thomas Schulz <thomas-k-schulz at t-online.de> wrote: > I am a NewBe - and i dont understand the Result. > Mathematica says that 34.123*89 = 3036.94699999997 but its 3036.947... > How can i change this? > > i use a IBook (G4) with Mac OS X. > THX > Thomas > Mathematica interprets decimal numbers like "34.123" in floating point. A floating-point number is, mathematically, an integer times a power of two. For different precisions, one has different restrictions on the integer and the exponent. We are accustomed to think of "34.123" as an integer times a power of 10, specifically, 34123 * 10^-3. Mathematica found the nearest floating point number,and apparently it happened to be slightly less that 34123/1000. If you had asked for (34123/1000)*89 you would have ot an exact result. Indeed, if you give Mathematica exact input and do not request a numerical approximation of the result, it will do its best to compute an exact answer even if this involves ridiculously big numerators and denominators. Try (34123/1000)^89. -- Chris Henrich Yes, one can rant about the program designs, but generally things keep getting more and more confused as time goes on. --Sea Wasp