incompatible type for argument 1

Question

I have this program, in C, and I get these errors:

calcularpi.c:37:2: error: incompatible type for argument 1 of 'media'

calcularpi.c:22:8: note: expected 'double *' but argument is of type 'double'

calcularpi.c:38:2: error: incompatible type for argument 1 of 'eam'

calcularpi.c:23:8: note: expected 'double ' but argument is of type 'double'

double genera_valor(double lim_inf, double rango);
int dentro_circunferencia(double x, double y);
double calcula_pi(long int num_puntos);
double media(double valores[100]);
double eam(double valores[100]);

int main(void){ 
 srand48(time(NULL)); // Inicializamos semilla
 long int num_puntos = 0; 
 double valores[100];
 int i=0;
 printf("Numero de puntos a generar: ");
 scanf("%ld",&num_puntos);
  while (i<100){
 valores[i] = calcula_pi(num_puntos);
 i++;
 }
 printf("El valor es: \n %lf", media(valores[100]));
 printf("El error es: \n %lf", eam(valores[100]));
}


double media(double valores[100]){
    double suma=0;
    int i;
    for (i=0;i<100;i++)
{
  suma=suma + valores[i];
}
return suma/100;   


}

double eam(double valores[100]){
int i=0;
double suma=0;
double errores[100];
  while (i<100)
{
errores[i]= fabs(M_PI - (valores[i]));
suma=suma+ errores[i];
i++;
}    
return suma/100;
}
double calcula_pi(long int num_puntos){
    int i=0;
    double min=-1;
    double puntoscircunferencia=0;
    double rango=2;
    double x=0;
    double y=0;
    while (i<num_puntos){
genera_valor(min, rango);
x=genera_valor(min,rango);
y=genera_valor(min,rango);
if (dentro_circunferencia (x, y)==1){
    puntoscircunferencia++;
}
i++;
}
    return (puntoscircunferencia*4)/num_puntos;
    }
double media(double valores[100]);

double genera_valor(double lim_inf, double rango){
   rango = 2;
   lim_inf = -1;
   double r=drand48();
double valor= lim_inf + rango * r;
return valor;
}

/* Comprueba si el punto esta dentro de la circunferencia.*/
int dentro_circunferencia(double x, double y){
    if(y<1-x*x){
        return 1;
    }
    else
        return 0;
        }

I'd like to know where is the array or variable problem, so I can finish the application. I think the rest is fine. Thanks.

Answer 1

Change:

printf("El valor es: \n %lf", media(valores[100]));
printf("El error es: \n %lf", eam(valores[100]));

to:

printf("El valor es: \n %f", media(valores));
printf("El error es: \n %f", eam(valores));

valores is your array, here, and decays in this context to type double * - valores[100] is the 101st element of your array (which is one more than the number of elements it actually has) and decays to type double. Since media() and eam() both accept a single argument of type double * (double media(double valores[100]); is equivalent to double media(double * valores);), that's why you're getting your type mismatch error.

Also %f is the more appropriate format specifier for double with printf(). This is different from scanf() and friends, where %lf would be correct.