Gablagar:
Is possible that I can do it a very great initialitation as:for (i=0;1<100000;i++){
ax[i]=0; ay[i]=0; az[i]=0;}
Only if you declare the arrays before you initialize them:
int ax[100000];
int ay[100000];
int az[100000];
Of course to do that you need a processor with over 600,000 bytes of SRAM. The 386P has 2,000 and the Mega (2560) has 8,000. You can add 512K of extra SRAM to the Mega but that would still not be enough.
Are you sure you have to have every value in memory before you an do your calculations?
If so you may need to process your data on a more capable machine.