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

#define MAX_COLUMNS 60

float xl, xu, delta, ymin, ymax;
int ch;

void print_header();
void get_domain_parameters();
void calculate_min_max();
void print_plot_header();
void print_plot_footer();
void print_plot();
double expon(double,int);
double fac(int);
double expp(double);

main()
{
  print_header();
  get_domain_parameters();
  calculate_min_max();
  print_plot();
  return 0;
}

double func(double x)
{
	if(ch==1)
		return sin(x);
	else if(ch ==2)
		return cos(x);
	else if(ch ==3)
		return sin(x)*cos(x);
	else
		return expp(x);
}


double expon(double x, int m)
{
	int j;
	double num = 1;
	
	for(j=0;j<m;j++)
		num = num * x;

	return num;
}

double fac(int m)
{
	double den=1;
	int j;
	for(j=0;j<m;j++)
		den = den * (j+1);
	
	return den;
}

double expp(double x)
{
	int n,i,j;
	double sum,den,num;
	n = 19;
	sum = 0;
	for(i=0;i<n;i++)
	{
		num = expon(x,i);
		den = fac(i);
		sum = sum + num/den;
	}
	return sum;
}

void print_header()
{
	printf("%f\n", expp(2));
  printf("\n==============================================\n");
  printf("            Function Plotting Program\n");
  printf("==============================================\n");
  printf("\n");
}

void get_domain_parameters()
{
	printf("Please select on of the following functions to plot:\n");
	printf("1. sin(x)\n2. cos(x)\n3. cos(x)*sin(x)\n4. exp(x)\nEnter choice: ");
	scanf("%d",&ch);
  printf("Please enter lower bound for domain: ");
  scanf("%f", &xl);
  printf("Please enter upper bound for domain: ");
  scanf("%f", &xu);
  printf("Please enter interval over domain: ");
  scanf("%f", &delta);

  printf("\nYou entered the following domain parameters:\n");
  printf(" ===========================================\n");
  printf("    Lower bound for domain: %f\n", xl);
  printf("    Upper bound for domain: %f\n", xu);
  printf("    Increment value       : %f\n", delta);
  printf(" ===========================================\n\n");
}

void calculate_min_max()
{
  float x, y;

  ymin = func(xl);
  ymax = func(xl);
  for (x = xl; x <= xu; x += delta) {
    y = func(x);
    if (y < ymin) ymin = y;
    if (y > ymax) ymax = y;
  }
}

void print_plot_header()
{
  printf("    %3.1f", ymin);
  printf("                           %3.1f", (ymin + ymax) / 2);
  printf("                            %3.1f\n", ymax);
  printf("      +");
  printf("-----------------------------+");
  printf("------------------------------+\n");
}

void print_plot_footer()
{
  printf("      +");
  printf("-----------------------------+");
  printf("------------------------------+\n");
  printf("    %3.1f", ymin);
  printf("                           %3.1f", (ymin + ymax) / 2);
  printf("                            %3.1f\n", ymax);
}

void print_plot()
{
  int scale_index, i, previous;
  float x;
  char A[MAX_COLUMNS];

  for (i = 0; i < MAX_COLUMNS; i++)
    A[i] = ' ';
  x = xl;
  previous = 0;
  print_plot_header();

  /*************************************************************/
  /* Loop through values of x in the domain, in incs of delta  */
  /*************************************************************/
  while (x <= xu) {

    /***********************************************************/
    /* Calculate scale_index: number of spaces to the left of  */
    /* the asterisk. Keep track of previous location of the    */
    /* asterisk. In each iteration, place a space in the       */
    /* previous location, and an asterisk in the current one.  */
    /***********************************************************/
    scale_index = (func(x) - ymin) * MAX_COLUMNS / (ymax - ymin) - 0.5; 
    A[previous] = ' ';
    A[scale_index] = '*';
    previous = scale_index;
    printf("%5.2f |", x);
    for (i = 0; i < MAX_COLUMNS; i++)
      putchar(A[i]);
    printf("|\n");
    x = x + delta;
  }
  print_plot_footer();
}