Re: Mathematica. A big limit of mathematica !!!???


LumisROB wrote:
> During this calculation:
>
>
> m= Table[ (i-j)+3.*j^-4 +50*i , {i,1,10000} , {j,1,10000} ];
> Det[m]
>
> the kernel has jammed and the following message has been visualized
>
> No more memory available.
> Mathematica kernel has shut down.

Do you realize that 10^8 elements should be generated in the table, each
element needing several bytes, because the dot after the "3"
means that you want floating point numbers? Just storing
m will require at least several Gigabyte memory.
Do you have such a computer? Probably not since Mathematica already
told you "No more memory available".

But this effort appears unnecessary because in your case your final
result should be exactly 0. Indeed the matrix m is a sum
of matrix with identical rows and a matrix with identical columns:
in such a case only 1 or 2-dimensional matrices may have
non-zero determinant since the spanned vector space is 2-dimensional.


>
> It is not a banal problem, more times I encounter me with these
> problems that really make unusable Mathematica for my purposes . In
> such cases I am forced to pass to Matlab that is behaved better
> always. But I love Mathematica and I want to look for a solution not
> to abandon it
> Precise that know Mathematica enough to fund and therefore I am not
> scandalized me if in such problems the time of calculation lengthens
> but really I don't understand because in reality it jams
> Precise that have introduced more times this problem in numerous
> occasions and anybody has ever known how to give me a satisfactory
> explanation. Obviously I don't expect me that Mathematica is as fast
> as a compiled program but that that expect me from a so valid program
> it is that if it don't succeed in completing a calculation point out
> me the reality motive.
> Is it a wrong thing to pretend it?
>
> The dimension of the in demand memory is not limited from windows xp
> or my hardware-software(OS) configuration, in fact such error also
> happens in xp 64 Bit with Mathematica 5.2 (64 Bit) Athlon 64 2 GB Ram.
>
> Is it probably a big limit of mathematica in to manage data of big
> dimensions ?
> Are these problems the true limit of mathematica ?
> Is it possible to overcome this obstacle? ……or Where am I being wrong?
>
>
> Thanks for the help
>
>
.

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