Something

typedef struct T_NUMVECT
{
  int vsize;
  double eps;
  double *v;
}
t_numv;

t_numv* numv_init(void)
{
  t_numv *numv = malloc (sizeof( t_numv ));
  numv->vsize = 0;
  return numv;
}

int numv_append(t_numv *numv, double val)
{
  numv->vsize++;
  if((numv = realloc(numv->v, numv->vsize) == NULL)
    return E_BAD_ALLOC;

  numv->v[numv->vsize - 1] = val;
  return E_OK;
}