very large objects

[n00buk]

Hi,
sorry for being a complete beginner.

I want to create a very large object.
If it were possible for example an array:
float thingy[6000][6000][50];

Since that is too large for an array I created nested vectors of the same dimensions:

int K=50, J=6000;

// create a vector of zeros of length K
vector <float> addK; 
for (int i=0;i<K;i++){addK.push_back(0);}

// create a matrix of zeros of dimension JxK
vector < vector <float> > addJK;
for (int i=0;i<J;i++){addJK.push_back(addK);}

// create a matrix of zeros of dimensions JxJxK
vector < vector < vector <float> > > big;
for (int i=0;i<J;i++){
big.push_back(addJK);}

But this is way too slow to work with.
The memory seems to be full half way through

Is there a way to do this efficiently?
Maybe a way to split this big "matrix" up?

Thanks a lot

[Moschops]

Since that is too large for an array

Only on the stack. If you use new you can have that (provided you've got 8GB of RAM, that is - 6000*6000*50*4 bytes per float = a bit under 7GB, or a bit under 14GB if you're using 8 byte floats). That said, multi-dimensional arrays are a pig.

[Mathhead200]

What are you trying to do? Why do you need so much RAM?

Possible fixes:
1) Find a way to work with the data one at a time, so you don't need it all in memory at once.
2) Declare it in program memory, instead of on the stack.
3) Use the hard drive, instead of RAM.
etc...