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

/* This is a comment enclosed in special symbols */
/* Notice:
	1. The way variable names have been  chosen. The names make sense.
	2. Insert comments about your program. It makes reading of 
		the program easy.
	3. Look at the program indentation. Very important.
	4. Within a single program some blanks lines are inserted so
		that the program looks paragraphed.
*/

#ifdef P1
/* This program converts Celsius to Fahrenheit. */
/* Since Celsius and Fahrenheit both can be real numbers
   we choose 'float' data type for these. */

main()
{
	float Celsius;
	float Fahrenheit;

	printf("Input temperature in Celsius --> ");
	scanf("%f",&Celsius);
	Fahrenheit = (9.0/5.0)*Celsius+32;
	printf("%f Celsius = %f Fahrenheit\n",Celsius,Fahrenheit);
}

/* If you write only (9/5), compiler does an integer division
	and produces integral answer of 1. To prevent this write at
	least one of the two constants as 'float' numbers that is either
	(9.0/5) or (9/5.0) or (9.0/5.0). */
	
#endif

#ifdef P2
/* This program calculates the time required by a ball to reach
   ground if dropped from a height h */

main()
{
	float Height;
	float Time;

	printf("Input height in meters --> ");
	scanf("%f",&Height);
	if ( Height >= 0.0 )
	{
		Time = sqrt(2*Height/9.8);
		printf("Time required = %f seconds\n",Time);
	}
	else
		printf("Height must be nonnegative\n");
}	
#endif

#ifdef P3
/* This program calculates income taxes. */
/* We dont worry too much about paise. So we choose int data type for
   income and tax. */
main()
{
	int Income;
	int Tax;

	printf("Input income in Rupees (Rounded) --> ");
	scanf("%d",&Income);
	/*     ^^^ %d here and not %f */

	if ( Income >= 150000 )
	{
		Tax = 19000 + (Income - 150000)*0.3;
	}
	else
	{
		if ( Income >= 60000 )
			Tax = 1000 + (Income - 60000)*0.2;
		else
			if ( Income >= 50000 )
				Tax = (Income - 50000)*0.1;
			else
				Tax = 0;
	}
	printf("Net Tax = %d Rs\n",Tax);
}

#endif

#ifdef P4
/* This program calculates sine function */
/* All variables are float type. Why? */
main()
{
	float Degrees;
	float Radians;
	float SineValue;
	float Pi;

	printf("Enter angle in degrees --> ");
	scanf("%f",&Degrees);
	/* Calculate value of pi using tan inverse function */
	Pi = 4.0 * atan(1.0);
	Radians = Degrees * Pi / 180.0;
	SineValue = Radians - pow(Radians,3)/6.0 + pow(Radians,5)/120.0;
	if ( Radians < Pi / 2 ) 
		printf("sin(%f) = %f\n",Degrees,SineValue);
	else
		printf("sin(%f) = %f (Approximately)\n",Degrees,SineValue);
}

#endif