Re: How do I really get rid of previous results?
- To: mathgroup at smc.vnet.net
- Subject: [mg29564] Re: How do I really get rid of previous results?
- From: "Orestis Vantzos" <atelesforos at hotmail.com>
- Date: Mon, 25 Jun 2001 20:42:17 -0400 (EDT)
- Organization: National Technical University of Athens, Greece
- References: <9h66m1$l50$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Mathematica keeps a hidden cache of previous computations, regardless of cleaning operations (such as Clean and Remove) performed by the user. What you need is Developer`ClearCache[] (in V4 or 4.1 ofcourse). Orestis "Fred Simons" <f.h.simons at tue.nl> wrote in message news:9h66m1$l50$1 at smc.vnet.net... > When studying the very interesting approach of Adam Strzebonski to the > question raised by Maarten van den Burg of finding all real roots of an > equation, I ran into the following problem. > > As done by Adam Strzebonski , I define a polynomial and a list of roots. > > poly=x/20+Normal[Series[Cos[x],{x,0,100}]]; > rts=Table[Root[poly,i],{i,14}];//Timing > > {1.82 Second,Null} > > Finding the numerical values of the elements of the list takes some time: > > N[rts] // Timing > > {27.9 > Second,{-38.9752,-19.1433,-18.4538,-13.4028,-11.6152,-7.47114,-4.96317,-1.49 > 593,1.65357,4.48616,8.28087,10.446,14.984,16.324}} > > I want to redo this computation. > > ClearAll[poly, rts];Remove[poly, rts] > > I redefine the polynomial and the table. Now the construction of the table > is more than three times as fast. > > poly=x/20+Normal[Series[Cos[x],{x,0,100}]]; > rts=Table[Root[poly,i],{i,14}];//Timing > > {0.55 Second,Null} > > And Mathematica still knows the values of my removed table: > > N[rts] // Timing > > {0. > Second,{-38.9752,-19.1433,-18.4538,-13.4028,-11.6152,-7.47114,-4.96317,-1.49 > 593,1.65357,4.48616,8.28087,10.446,14.984,16.324}} > > It has nothing to do with the removal of the names, as we see by using > different names: > > rts2=Table[Root[poly,i],{i,14}];//Timing > > {0.55 Second,Null} > > N[rts2] // Timing > > {0. > Second,{-38.9752,-19.1433,-18.4538,-13.4028,-11.6152,-7.47114,-4.96317,-1.49 > 593,1.65357,4.48616,8.28087,10.446,14.984,16.324}} > > What is going on here, and how do I avoid this behaviour? > > Fred Simons > Eindhoven University of Technology > >