Re: Massive memory issues when using Det

*To*: mathgroup at smc.vnet.net*Subject*: [mg127324] Re: Massive memory issues when using Det*From*: Jonathan Frazer <J.Frazer at sussex.ac.uk>*Date*: Tue, 17 Jul 2012 01:30:05 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net*References*: <20120711061823.1AE5D684B@smc.vnet.net>

Also, I was trying to work out how to use the parallel computing options but when I tried Parallelize[Det[g]] Mathematica said no. How do I know if something is parallelizable or not? Sorry for the stupid questions. This is all rather new to me. Thank, Jonny On 16 Jul 2012, at 12:04, wrote: > Hi > > I'm having a lot of trouble calculating the determinant of even a 3x3 matrix. The expressions are large but all aspects of the program are handling them fine except Det. > > Is Det trying to simplify the expressions by any chance? Is there anything I can try? Below is an example of how I construct the matrix but this example is much simpler. The difference is S\theta\alpha and C\theta\alpha are bigger expressions in the real thing. As far as I can tell the code is logically fine. It works for smaller dimension problems with no trouble at all. > > Right now I have been trying to evaluate Det for about 3 hours and its taking up almost 12 GB of memory. > > Thanks in advance, > > Jonny > > On 11 Jul 2012, at 18:39, wrote: > >> d = 2; >> èá = Table[Symbol["è" <> ToString[i]], {i, d - 1}]; >> Sèá = Sin[èá]; >> Cèá = Cos[èá]; >> sè = r Prepend[Table[Product[Sèá[[á]], {á, i}], {i, d - 1}], 1]*Append[Cèá, 1]; >> ë = Outer[D[#1, #2] &, sè, èá]; >> g = Table[Sum[ë[[ã, á]] ë[[ã, â]], {ã, d}], {á, d - 1}, {â, d - 1}]; >> vol = Sqrt[Det[g]] >> >

**References**:**Re: Epilog and ListPlot3D***From:*Bill Rowe <readnews@sbcglobal.net>