Re: "+ -" in an output line?

*To*: mathgroup at smc.vnet.net*Subject*: [mg52298] Re: [mg52275] "+ -" in an output line?*From*: yehuda ben-shimol <benshimo at bgu.ac.il>*Date*: Sun, 21 Nov 2004 07:23:40 -0500 (EST)*References*: <200411200841.DAA08791@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Out[13] is not kept as a standard "Mathematical expression". It is kept within a header of a SeriesData as you can see below. The - comes from the Complex[0,-1] and the + comes (probably) from some sort of displaying this object as a mathematical expression on the screen but not evaluated.. Running the following commands a = Series[-I q s - I p Sqrt[K12 - s2], {s, 0, 1}]; FullForm[a] SeriesData[s, 0, List[Times[Complex[0, -1], p, Power[Plus[K12, Times[-1, s2]], Rational[1, 2]]], Times[Complex[0, -1], q]], 0, 2, 1] will show you that. But if you run b = Normal[a]; FullForm[b] Plus[Times[Complex[0, -1], q, s], Times[Complex[0, -1], p, Power[Plus[K12, Times[-1, s2]], Rational[1, 2]]]] you can notice that this is an evaluated regular expression of Mathematica Anyway, I think that this should not appear and hope it will be corrected yehdua AES/newspost wrote: >The input > > In[13]:= > Series[-I q s - I p Sqrt[K1^2 - s^2], {s, 0, 1}] > >gives > > Out[13]= > -I Sqrt[K1^2] p + - I q s + O[s^2] > >whereas > > In[14]:= > Series[-I q s - I p Sqrt[K1^2 - s^2], {s, 0, 1}] // Normal > >gives > > Out[14]= > -I Sqrt[K1^2] p - I q s > >What's that "+ -" doing in Out[13] ? Is this normal? > > >

**References**:**"+ -" in an output line?***From:*AES/newspost <siegman@stanford.edu>