text: #ifndef UTILS_H
  #define UTILS_H
    
  #include <stdint.h>
  #include <complex.h>
  
  typedef double complex CPX;
  #define rand01() ((double)rand()/RAND_MAX)
  
  void dzero(int n, double *a);
  void czero(int n, CPX *a);
  
  void comp_err_helm(int n,int pg, int pgt, CPX *pot, CPX *potex, CPX *pottarg, CPX *pottargex,
           CPX *grad, CPX *gradex, CPX *gradtarg, CPX *gradtargex, double *err);
  
  void comp_err_lap(int n,int pg, int pgt, double *pot, double *potex, 
           double *pottarg, double *pottargex, double *grad, 
           double *gradex, double *gradtarg, double *gradtargex, double *err);
  #endif
  