#include <stdio.h>
#include <math.h>
void initial (int, char*);
double integrate (double (*)(double), double, double);

double integrate (double (*fptr)(double), double a, double b) {
	double x, sum = 0.0, delta_x = 0.1;
	for (x = a; x <= b; x = x + delta_x)
		sum = sum + delta_x * (*fptr)(x);
	return sum;
}

void initial (int x, char* y) {
	printf ("fewer than %d chars in %s\n", x, y);
}
int main (void) {

	double (*fptr)();		
						/* want a pointer to a function not */
	void (*funptr)();		/*a function that returns a pointer */
	
	funptr = initial;
	
	initial (64, "Help me, please?") ;
	(*funptr) (24, "Why, Oh why?") ;
										/* next example*/
	fprintf (stdout, "Integral of sine is %f\n", 
				integrate (sin, 0.0, 1.1));
	
	fptr = cos;
	fprintf (stdout, "Cosine integral is %f\n", 
				integrate ((*fptr), 0.0, 1.1));
	return 0;
}
/*
fewer than 64 chars in Help me, please?
fewer than 24 chars in Why, Oh why?
Integral of sine is 0.590509
Cosine integral is 0.963144
*/