Re: How do twice Working Precision in square operation
- To: mathgroup at smc.vnet.net
- Subject: [mg86125] Re: [mg86002] How do twice Working Precision in square operation
- From: danl at wolfram.com
- Date: Sun, 2 Mar 2008 13:58:16 -0500 (EST)
- References: <200802291122.GAA19237@smc.vnet.net>
> Who know how forced double numerical precision in operation ^2 or > triple in ^3 > e.g. we have number with precision 300 digits after comma and we do > square of this number > > N[-23.83242089169940112293636352304345516242356370829658528533245578869781207629749826968513219545485106785646817025052324254382671446440221122018213525849182937524917564915820784936033688847601879751439448736954164351572578669610243156800163244111408628195484090841094436992490050778`263.90219946983575^2,600] > > I want received WorkingPrecision->600 > > How do that on Mathematica ? > > BEST WISHES > ARTUR Call the input nn. You could do nn2 = SetPrecision[nn^2, 600] but the digits added will be garbage. Well, actually what gets appended are zeros in base 2 (which, numerically, are garbage, but not random garbage). You can see this by looking at RealDigits[nn2, 2]. If you question involves wanting to see justifiable digits, you cannot because, mathematically, they do not exist. Mathematica is showing all digits that are justified (up to a fairly reliable first order approximation of error, if you want to get a bit technical). Daniel Lichtblau Wolfram Research