segmentation fault 에러 도움 부탁드립니다.

#include <stdio.h>
#include <math.h>
#include <stdlib.h>
 
#define GM 1
#define Tfin 1
 
double h=0.001;
 
double x0[5][3]={{0,0,0},{0,1,2},{3,4,5},{4,5,2},{3,1,2}};
double v0[5][3]={{0,0,0},{2,-1,3},{3,4,2},{2,1,-2},{7,2,1}};
double **x,**v;
double **a,angm[3]={0,0,0};
double t;
 
int main(){
 
for(int i=0;i<5;i++){
	x[i]=x0[i];
	v[i]=v0[i];
}
 
t=0;
 
}