A = -4; B = (4-1)/2.0; C = 2;
define f(x) { return(A  + B*(x-2) + C*power(x-2,2));}

define df(x) {return(B + 2*C*(x-2));}


define o(n) {if (n==0) return 0; else return(1/n);}

define lista(x, n, fim)
{
local Deltaf;
	printf(" x  Delta  Deltaf/Delta \n");
while (n < fim)
{
	Deltaf = f(x + o(n)) - f(x);
	printf("%f,   %f,      %f;      \n",  x,o(n), Deltaf/o(n));
	n = n + 2;
}
printf("%f \n", df(x)  );
printf("%f \n", Deltaf/o(n)  );
printf("%f \n", df(x) - Deltaf/o(n) );
}

a = 2;
print "derivada aproximada em ",a;
lista(a,1,20);

quit;