// ITI 1120 Winter 2012, Lab 5, Example 3
// Name: Gilbert Arbez, Student# 1234567

import java.io.*;

/**
 * This program finds the distance a ball thrown with fixed initial velocity
 * travels for various angles from the horizontal.
 */

class Lab5Ex3
{
  public static void main (String[] args)
  {
    // DECLARE VARIABLES/DATA DICTIONARY     
    double velocity;  // Initial velocity of ball (m/s)
    double[] ranges;   // Ranges travelled for various angles (m)
    int theta;        // anle of release
    int index;       // for traversing array
    
    // PRINT OUT IDENTIFICATION INFORMATION    
    System.out.println();
    System.out.println("ITI 1120 Winter 2012, Lab 5, Example 3");
    System.out.println("Name: Gilbert Arbez, Student# 1234567");
    System.out.println();    
    
    // READ IN GIVENS   
    System.out.println( "What is the initial velocity of the ball (m/s)?" );
    velocity = ITI1120.readDouble();
       
    // Call problem solving method
    ranges = calculateRanges(velocity);
       
    // PRINT OUT RESULTS AND MODIFIEDS
    theta = 0;    
    while ( theta <= 90 )
    {
      System.out.println( "For angle " + theta + " degrees, ball travels " + ranges[theta/10] + " metres." );
      theta = theta + 10;
    }
  }//end main
  
  
  /* 
   * Method:  calculateRanges
   * Description: Calculate the range of thrown ball for the given velocity
   *              at different angls.
   * Givens: v - initial velocity of the ball.
   */
  public static double[] calculateRanges(double v)
  {
    // Results
    double[] ranges;   // Reference to array of ranges travelled for various angles (m)    
    // Intermediates
    int theta;        // Horizontal angle of ball (degrees)
    double thetaRad;  // Horizontal angle of ball (radians)
    double degToRad;  // Constant:  degrees to radians multiplier
    double g;         // Constant:  acceleration due to gravity  (m/s^2)
    
    // Body
    g = 9.8;                     // Constant:  gravity acceleration 
    degToRad = Math.PI/180.0;  // Constant:  degrees -> radians    
    ranges = new double[10];
    
    // Note that theta is an int, while thetaRad is a double.  This makes the loop reliable.    
    theta = 0;    
    while(theta <= 90)
    {
      thetaRad = degToRad * theta;
      ranges[theta/10] = 2.0*v*v*Math.cos(thetaRad)*Math.sin(thetaRad)/g;
      theta = theta + 10;
    }
    
    // return the results, a reference to the array
    return(ranges);
  }
  
} //end class