#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <conio.h>

double dia,speed;

double circum;
double freq;

double pi=atan2(0.,-1.);

int iunit_speed;
int iunit_dia;


FILE *pFile[6];
char filename[6][FILENAME_MAX];

void main()
{

	printf("\n\n tire.cpp   ver 1.0   October 12, 2007 ");
	printf("\n by Tom Irvine   Email: tomirvine@aol.com \n");

	printf("\n This program caclulates the vibration frequency of ");
	printf("\n a tire due to imbalance at a given speed. \n");


	printf("\n Select speed unit: ");
    printf("\n 1=mph  2=feet/sec  3=km/hr \n");
	scanf("%d",&iunit_speed);


// **************************************

// convert speed to m/sec

	if(iunit_speed==1)
	{
		printf("\n\n Enter speed (mph)\n");
		scanf("%lf",&speed);
		speed*= 0.44704;
	}
	if(iunit_speed==2)
	{
		printf("\n\n Enter speed (ft/sec)\n");
		scanf("%lf",&speed);
		speed*= 0.3048;
	}
	if(iunit_speed==3)
	{
		printf("\n\n Enter speed (km/hr)\n");
		scanf("%lf",&speed);	
		speed*= 0.27778; 
	}


	printf("\n Select diameter unit: ");
    printf("\n 1=in  2=cm  \n");
	scanf("%d",&iunit_dia);	
	

// convert diameter to m

	if(iunit_dia==1)
	{
		printf("\n\n Enter diameter (inch) \n");
		scanf("%lf",&dia);
		dia*=0.0254;
	}
	if(iunit_dia==2)
	{
		printf("\n\n Enter diameter (cm) \n");
		scanf("%lf",&dia);	
		dia*=0.01 ;
	}


// **************************************

	circum = pi*dia;

	freq = speed/circum;

	printf("\n freq = %8.4g Hz\n",freq); 



	printf("\n Press any key to exit \n");

	getch();
	exit(1);
}