Re: Slowdown

*To*: mathgroup at smc.vnet.net*Subject*: [mg53223] Re: Slowdown*From*: Peter Pein <petsie at arcor.de>*Date*: Sat, 1 Jan 2005 02:33:43 -0500 (EST)*References*: <cr33tt$je6$1@smc.vnet.net>*Sender*: owner-wri-mathgroup at wolfram.com

Maxim wrote: > Consider: > > In[1]:= > Module[{f, L}, > L = f[]; > Do[L = f[L, i], {i, 10^4}] > ] // Timing > > Module[{weirdness, L}, > L = weirdness[]; > Do[L = weirdness[L, i], {i, 10^4}] > ] // Timing > > Out[1]= > {0.015*Second, Null} > > Out[2]= > {3.063*Second, Null} > > Here the timings differ by a factor of 200. Besides, the timing grows > linearly in the first case and quadratically in the second (therefore, for > n=10^5 there will be an approximately 2000 times slowdown). We can only > guess that something goes wrong with the symbol name hashing. > > Maxim Rytin > m.r at inbox.ru > Your version of Mathematica may be too up to date ;-) In[1]:= $Version Out[1]= "4.0 for Microsoft Windows (July 16, 1999)" In[2]:= Module[{f, L}, L = f[]; Do[L = f[L, i], {i, 10^6}]] // Timing Out[2]= {1.547 Second, Null} In[3]:= Module[{weirdness, L}, L = weirdness[]; Do[L = weirdness[L, i], {i, 10^6}]] // Timing Out[3]= {1.547 Second, Null} -- Peter Pein Berlin