//
// Formulae program
// 
// Author:      Kenneth Chan
// email :      kjc@liverpool.ac.uk
// Date  :      October 2011
// Description: program that solves some easy formula
// 

import java.util.Scanner ;

class formula
{
    static Scanner input = new Scanner( System.in ) ;

    ////////////////////////////////////////////////////
    // c2f: method to convert centigrade (celcius) to fahrenheit 
    ////////////////////////////////////////////////////
    static void c2f()
    {
        double celcius ;
        double fahrenheit ;

        System.out.println( "CENTIGRADE TO FAHRENHEIT CONVERSION" ) ;
        System.out.println( "Please enter degrees celcius: " ) ;
        celcius = input.nextDouble() ;
        fahrenheit = ((celcius*9)/5)+32 ;
        
        System.out.println() ;
        System.out.printf( "%12.5f celcius is %12.3f fahrenheit\n", 
                           celcius, fahrenheit ) ;
    }

    //
    // f2c: method to convert fahrenheit to centigrade
    //
    static void f2c()
    {
        double celcius ;
        double fahrenheit ;

        System.out.println( "FAHRENHEIT TO CENTIGRADE CONVERSION" ) ;
        System.out.print( "Please enter degrees fahrenheit: " ) ;
        fahrenheit = input.nextDouble() ;
        celcius = 5 * ( fahrenheit - 32 ) / 9 ;
        
        System.out.println() ;
        System.out.printf( "%8.3f fahrenheit is %6.3f celcius\n", 
                           fahrenheit, celcius ) ;
    }

    //
    // c1: method to calculate the circumference of circle
    //
    static void c1()
    {
        double radius ;
        double circumference ;
        final double PI = 3.14159 ;

        System.out.println( "CIRCUMFERENCE CALCULATION" ) ;
        System.out.print( "Please enter radius: " ) ;
        radius = input.nextDouble() ;
        circumference = 2*PI*radius ;
        
        System.out.println() ;
        System.out.printf( "radius = %8.4f, circumference = %8.4f\n",
                           radius, circumference ) ;
    }

    //
    // c2: method to calculate the area of circle using Math.PI 
    //
    static void c2()
    {
        double radius ;

        System.out.println( "CIRCLE AREA CALCULATION" ) ;
        System.out.print( "Please enter radius: " ) ;
        radius = input.nextDouble() ;
        
        System.out.println() ;
        System.out.printf( "radius = %8.4f, area = %8.4f\n",
                           radius, Math.PI*radius*radius ) ;
    }

    //
    // MAIN
    //
    public static void main( String args[] )
    {
        if ( args.length > 0 )
        {
            if ( args[0].indexOf( 'a' ) >= 0 ) c2f() ;
            if ( args[0].indexOf( 'b' ) >= 0 ) f2c() ;
            if ( args[0].indexOf( 'c' ) >= 0 ) c1() ;
            if ( args[0].indexOf( 'd' ) >= 0 ) c2() ;
        }
        else
        {
            System.out.println( "Usage: java formula [a][b][c][d]" ) ;
        }                     
    }
}