//Unit operaciones

double suma (double a, double b)
       {
       return (a+b);
       }

double resta (double a, double b)
       {
       return (a-b);
       }

double mult (double a, double b)
       {
       return (a*b);
       }

double div (double a, double b)
       {
       return (a/b);
       }

double mod (int a, int b)
       {
       return (a%b);
       }