Thread: from 2D array to 1D array

Hi there,

I need to use a function that requires a 1D array in entry; to do so I created a 1D array from my original 2D array in order to pass it to the function (consider that I cannot modify the function because it's part of a library that must be kept as it is), but with the obvious waste of memory.

In fact, when I am treating very large matrices (extremely large), I get to a segmentation fault that is more than likely due to the size of the 2D array plus the new writing of the 1D vector.

I would like to pass directly the original 2D array to the function that requires a 1D array.

In this pseudo code probably my need is clearer:

Code:

int n=... (very large number. It changes with different input files that I read from a previous part of my code)
int m=3;

//Original 2D array from my code:
double COORDS[n][5];   //Originally this array is dynamically allocated with malloc): double **VARS + dynamic allocation with malloc

//Definition of the calling function: void function(double *VARIABLES)

This is what I am doing now before passing the required 1D array to the function; and this is where I get a segmentation fault when using extremely large arrays:

Code:

       k = 0;
	for( i = 0; i<=nnodes-1; i++){	
		COORDSarray[k] = COORDS[i][0];
		COORDSarray[k+1] = COORDS[i][1];
		COORDSarray[k+2] = 0.0;
       	
	k=k+3;
	}

As said above, I would like to pass the 2D array as if its content were to be written in a 1D array

I hope someone can help. Please, ask me if something is not clear from my description

All the best
CFD