#  MathDemo.py  Copyright (c) Kari Laitinen

#  http://www.naturalprogramming.com

#  2006-05-21  File created.
#  2022-12-27  Converted to Python 3.


#  This program demonstrates the use of the mathematical functions
#  that are available as built-in functions and in modules math and random.

import math
import random

EARTH_RADIUS_IN_KILOMETERS  =  6379

an_angle_in_radians  =  math.radians( 45 )

sine_of_an_angle  =  math.sin( an_angle_in_radians )

print( "\n The sine of an angle of 45 degrees is %f"  %  \
                                             sine_of_an_angle )

diameter_of_the_earth  =  2  *  math.pi  *  EARTH_RADIUS_IN_KILOMETERS

#  Because our planet Earth is not exactly a ball, the
#  diameters and areas calculated below are approximate.

print( "\n Earth diameter in kilometers:   %15.0f" % diameter_of_the_earth, end="" )

print( "\n Earth diameter in miles:        %15.0f" %  \
                                           ( diameter_of_the_earth / 1.6093 ), end="" )

surface_area_of_the_earth  =  \
            4  *  math.pi  *  math.pow( EARTH_RADIUS_IN_KILOMETERS, 2 )

print( "\n Earth area in square kilometers:%15.0f"    %   \
                       surface_area_of_the_earth, end="" )
print( "\n Earth area in square miles:     %15.0f\n"  %   \
                   ( surface_area_of_the_earth / math.pow( 1.6093, 2 ) ), end="" )

a_random_integer  =  int ( ( random.random() * 50 ) )

print( "\n And here is a random integer in the range from 0 to 49:  %d\n"  %  \
                                                             a_random_integer )

#  The built-in method round() is able round numbers as humans do.
#  The int() method always rounds downwards.

print( "\n int( 34.56 ) evaluates to     %d"  %  int( 34.56 ), end="" )
print( "\n round( 34.56 ) evaluates to   %f"  %  round( 34.56 ) )

#  The 'ceiling' of a number is the next whole number

print( "\n math.ceil( 34.56 ) returns    %f"  %  math.ceil( 34.56 ), end="" )
print( "\n math.ceil( 12.34 ) returns    %f"  %  math.ceil( 12.34 ), end="" )
print( "\n math.ceil( 12.01 ) returns    %f"  %  math.ceil( 12.01 ), end="" )
print( "\n math.ceil( 12.00 ) returns    %f"  %  math.ceil( 12.00 ) )