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

/*
 * getint - reads an integer from keyboard
 *
 * Inputs: 
 *
 * Outputs:
 *   An int is returned representing the value read from the keyboard
 *
 * Notes:
 *   The stdin stream is flushed; no tyleahead allowed. Error checking includes
 *   whether or not an integer was entered.
 */

int getint(void)
   {
    int val;
    int check;
    int check2;

     
	do {
	     fflush(stdin);
	     check=scanf("%d", &val);
	     if(check==0) printf("You didn't type an integer :-( \n");
	   } while(check==0);

	return val;
   }


/*
 * getrealP - print a prompt and read a real number from keyboard
 *
 * Inputs: 
 *   prompt  - a charactor that includes the entire string to be print to screen
 *
 * Outputs:
 *   An real number is returned representing the value read from the keyboard
 *
 * Notes:
 *   The stdin stream is flushed; no tyleahead allowed. Error checking includes
 *   whether or not an number was entered and whether or not it exceeded the 
 *   minimum or the maximum. Prompt is printed to screen.
 */

double getrealP(const char *prompt)
   {
    double val;
    int check;


    printf("%s\n", prompt);

      do {
         fflush(stdin);
	 check=scanf("%lf", &val);
	 if(check==0) printf("You didn't type an number: \n");
	 } while(check==0);
    
      
    return val;
   }



void main(void)
{

    double x1, x2, v1, v2, m1, m2, kd1, kd2, ks1, ks2, ks3, kd3, dt, F, dx1, dx2, dv1, dv2;
    int i;
    int g;
    int steps;


    kd1= getrealP("Enter value of kd1:\n ");
    kd2= getrealP("Enter value of kd2:\n ");
    kd3= getrealP("Enter value of kd3:\n ");
    ks1= getrealP("Enter value of ks1:\n ");
    ks2= getrealP("Enter value of ks2:\n ");
    ks3= getrealP("Enter value of ks3:\n ");
    m1 = getrealP("Enter value of Mass 1:\n ");
    m2 = getrealP("Enter value of Mass 2:\n ");
    F = getrealP("Enter a value for F:\n");
    dt = getrealP("Enter the desired size for dt: \n");

    printf("Enter the number of steps to use: \n\n");
    steps = getint();

	x1 = 0; 
	x2 = 0; 
	v1 = 0; 
	v2 = 0;


    for(i=0;i<steps;i++)
    {
      dx1 = v1;
      dx2 = v2;

      dv1 = v1*((-kd1-kd2)/m1) + x1*((ks1-ks2)/m1) + v2*(ks2/m1)+x2*(ks2/mass1);
      dv2 = (F/m2) + v2*((-kd2-kd3)/m2)+x2*((-ks2-ks3)/m2)+v1*(kd2/m2)+x1*(ks2/m2);

      x1 =x1+dt*dx1;
      x2 =x2+dt*dx2;
      v1 =v1+dt*dv1;
      v2 =v2+dt*dv2;


    }

       printf("V1 is: %lf \n", v1);
       printf("V2 is: %lf \n", v2);
       printf("X1 is: %lf \n", x1);
       printf("X2 is: %lf \n", x2);
}