Re: What does +- mean?
- To: mathgroup at smc.vnet.net
- Subject: [mg47581] Re: What does +- mean?
- From: drbob at bigfoot.com (Bobby R. Treat)
- Date: Fri, 16 Apr 2004 05:21:33 -0400 (EDT)
- References: <c5lfbm$bq2$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Look at the output of Series[Sqrt[-1/2 + x^2], {x, 0, 4}]; % // FullForm FullForm[SeriesData[x, 0, {Complex[0, 1]*1/Sqrt[2], 0, (Complex[0, -1])*1/Sqrt[2], 0, (Complex[0, Rational[-1, 2]])* 1/Sqrt[2]}, 0, 5, 1]] and pick out the second term: Times[Complex[0, -1], Power[2, Rational[-1, 2]]] -(I/Sqrt[2]) Notice the Complex number is negative and the Real part is positive, but "-+" has been resolved to "-" rather than "+-" -- as it should be. I'd say this is a bug, but it only affects DISPLAY of the Series. Bobby Lautaro Vergara <lvergara at lauca.usach.cl> wrote in message news:<c5lfbm$bq2$1 at smc.vnet.net>... > Hi, > > I have found (v. 5.0) an extrange thing: when one expands, e.g., > > Series[Sqrt[-1/2+x^2],{x,0,4}] > > there appear a +- sign (which is correctly not present when one changes > -1/2 by -1) > > is this a bug or a feature? > > Thanks > > L. Vergara