// 
// Chris Hough
// 
// Final Program 1 - Write a C program to integrate the area beneath the function below:
// f(t) = 5t+(sin(9t-5))/t
// September 16, 2003

#include <stdio.h>
#include <math.h>

double 	step,
	t_start,
	t_end,
	t_delta,
	t = 0,
	total_area = 0,
	i = 0,
	function;

double main(void)	{

	printf("Please enter the starting point of the function:  ");
	fflush(stdin);
	scanf("%lf", &t_start);
	
	printf("Please enter the ending value of the function:  ");
	fflush(stdin);
	scanf("%lf", &t_end);

	printf("Please enter the number of steps:  ");
	fflush(stdin);
	scanf("%lf", &step);

	t_delta = (t_end - t_start) / step;
	
	
	for(i = 0; i < step; i++)	{
		
		t = t_start + i * t_delta;
		function = (5 * t) + ((sin (9 * t - 5)) / t);
		
		if (i == 0)	total_area = total_area + function;

		if (i == step)	total_area = total_area + function;

		else	total_area = total_area + 2 * function;
	}

	total_area = total_area * t_delta / 2;

	printf("The total area under the curve is:  %lf", total_area);

	return total_area;
}