allocation of four dimensional array memory

[ahm_irf]

I need four dimensional array like
double a[256][256][256][256];


but the size is too big to use an array.

If I use only pointer like
double ****a;

to allocate this memory, I have to run 3 loops to allocate memory ..which takes lots of time.
a = (double **** ) malloc (sizeof(double ***)*256);
for(i=0;i<256;i++)
{
a[i] = (double ***) malloc ( sizeof(double **)*256);
for(j=0;j<256;j++)
{
a[i][j] = (double **) malloc ( sizeof(double *)*256);
for(k=0;k<256;k++)
{
a[i][j][k] = (double *) malloc ( sizeof(double )*256);
}
}
}


is there any other work around ....?

I was thinking to use *a[256][256][256]
Can I use this ...and if yes how I can allocate the memory for this...?

[ppesci]

Anyway, the memory needed by any method is about 32GB, that is:

256*256*256*256*8

Your RAM + swap space must be greater than 32GB. If you doesn't have that much memory, think to using your HD to allocate portions of the array, and load/save on demand.

HTH

[stevea]

But the 32GB is not even addressable unless he's got a processor with PAE, otherwise it 4GB per process max.


Perhaps if ahm_irf described what he is trying to do I could point him in a better direction.