Strange memory behavoir of Norm
- To: mathgroup at smc.vnet.net
- Subject: [mg109094] Strange memory behavoir of Norm
- From: Patrick Scheibe <pscheibe at trm.uni-leipzig.de>
- Date: Mon, 12 Apr 2010 23:00:49 -0400 (EDT)
Hi,
a user of another forum brought my attention to a memory leak which I
cannot explain. For real-valued numbers x1, x2 and x3 the following is
the same
Norm[{x1, x2, x3}]
Norm[{{x1}, {x2}, {x3}}]
Can someone confirm and maybe explain the following behavoir? I checked
it on Linux and OSX with Mathematica 7.
usedmema = MemoryInUse[];
Block[{a = {1., 1., 1.}},
Nest[Norm[a] &, Null, 10^6];
];
(MemoryInUse[] - usedmema)/2^20.
gives here 0.00259399 while
usedmema = MemoryInUse[];
Block[{a = {{1.}, {1.}, {1.}}},
Nest[Norm[a] &, Null, 10^6];
];
(MemoryInUse[] - usedmema)/2^20.
gives 122.075 MB of used memory. Expanding the definition of
Norm[{{x1}, {x2}, {x3}}]
and testing this
usedmema = MemoryInUse[];
Block[{a = {1., 1., 1.}},
Nest[Sqrt[
a[[1]]*Conjugate[a[[1]]] + a[[2]]*Conjugate[a[[2]]] +
a[[3]]*Conjugate[a[[3]]]] &, Null, 10^6];
];
(MemoryInUse[] - usedmema)/2^20.
gives no memory leak with 0.00299072MB.
Any ideas?
Cheers
Patrick