# HG changeset patch
# User Shantanu <shantanu@fossee.in>
# Date 1271852260 -19800
# Node ID 8e02b76cf068a4329ab2e0ddbccbe064dce69098
# Parent  25248b12f6e4bc1ee6a632427ccbe1345a89c016
Number data types scripts.

diff -r 25248b12f6e4 -r 8e02b76cf068 basic-python.txt
--- a/basic-python.txt	Wed Apr 21 17:34:01 2010 +0530
+++ b/basic-python.txt	Wed Apr 21 17:47:40 2010 +0530
@@ -146,10 +146,4 @@
 17/2.0 
 8.5
 17.0/2.0 
-8.5 
-
- 
- 
-
-
-  
+8.5   
diff -r 25248b12f6e4 -r 8e02b76cf068 numbers.org
--- a/numbers.org	Wed Apr 21 17:34:01 2010 +0530
+++ b/numbers.org	Wed Apr 21 17:47:40 2010 +0530
@@ -8,38 +8,82 @@
 *** Script
     Welcome friends. 
     
-    In this tutorial we shall look at data types available in Python and 
-    how to perform simple Input and Output operations. 
-    for 'Numbers' we have: int, float, complex datatypes
-    for Text content we have strings.
+    In this tutorial we shall look at data types in Python and 
+    mathematical operators available.
+    For 'Numbers' we have: int, float, complex datatypes    
     For conditional statements, 'Booleans'.
     
     Lets get started by opening IPython interpreter. 
     Lets start with  'numbers'
-    All integers irrespective of how big they are, are of 'int'
-    data type
-    Now we will create a variable, say
+    All integers irrespective of how big they are of 'int' data 
+    type. Now we will create a variable, say
     x = 13
     print x
 
     To check the data type of any variable Python provides 'type' function
     type(x)
     
+    lets create one more variable
     y = 999999999999
+    (what about large value? and it is Long and not int, should we mention
+    that?)
     print y
     
-    Floating point numbers comes under 'float'
+    Floating point numbers come under 'float'
     p = 3.141592
     type(p)
 
     Python by default provides support for complex numbers. 
     c = 3+4j 
-    c is a complex number. 'j' is used to specify the imaginary part.
+    creates a complex number c. Here 'j' is used to specify the imaginary 
+    part.
     type(c)
     Python also provides basic functions for their manipulations like
     abs(c) will return the absolute value of c(sqrt(a^2 + b^2))
     c.imag returns imaginary part and c.real gives the real part. 
+    
+    All the basic operators work with Python data types, without any
+    surprises. When we try to add two numbers like x and y Python takes 
+    cares of returning 'right' answer and we dont have to worry about
+    boundary conditions.
+    x + y
+    
+    % operator is for modulo operations
+    1786 % 12 gives 10
+    45 % 2 returns 1
 
+    Same as additions multiplication also works just right:
+    3124 * 126789
+    396088836
+    
+    x ** y returns x raised to power y. For example lets try:
+    big = 1234567891234567890 ** 3
+
+    Division in Python truncates, that is, when we divide a integer 
+    variable with another integer result is also integer and decimal 
+    value is truncated. So
+    17 / 2 returns 8 and not 8.5
+
+    but
+    17 / 2.0 will return the correct 8.5, similarly
+    17.0 / 2 will also give correct answer.
+    
+    Other operators which comes handy are:
+    += 
+    lets create one variable a with
+    a =  7546
+    now
+    a += 1 will increment the value of 'a' by 1
+    similarly 
+    a -= 1 will decrement.
+    we can also use 
+    a *= 2
+    a 
+    answer is multiplied by 2
+    
+    a /= 5    
+    a is divided by 5
+    
     Next we will look at Boolean datatype:
     Its a primitive datatype having one of two values: True or False.
     t = True
@@ -50,7 +94,7 @@
     
     f = not True
     
-    we can do binary operation like 'or' and 'not' with these variables
+    we can do binary operation like 'or', 'and', 'not' with these variables
     f or t
     f and t
     
@@ -65,8 +109,38 @@
     a and (b or c)
     False
 
-    we come to the end of this tutorial on introduction of Data types in
-    Python. In this tutorial we have learnt what are supported data types, 
-    supported operations and performing simple IO operations in Python.
+    We also have support for relational and logical operators. Lets try some
+    examples:
+    We start with initializing three variables by:
+    p, z, n = 1, 0, -1 
+    To check equivalency of two variables use '=='
+    p == z 
+    False
+    p >= n
+    True
+    
+    We can check for multiple logical operations in one statement itself.
+    n < z < p
+    True.
+    This statement checks if 'z' is smaller then 'p' and greater then 'n'
+    For inequality testing we use '!'
+    p + n != z will add 'p' and 'n' and check the equivalency with z
+
+    We have already covered briefly in some of the previous sessions, 
+    conversion of data among different types.
+    int(17 / 2.0) will convert result to integer type and we get
+    8 as answer and not 8.5
+    But if we try something like 
+    float(17 / 2) we get 8.0 as 17/2 is already truncated to int
+    and converting that to float wont restore the lost decimal digits.
+    To rounding off a floating number to a given precision 'round' function
+    can be used.
+    round(7.5) returns 
+    8.
+    
+    This brings us to the end of tutorial on introduction of Data types 
+    related to numbers in Python. In this tutorial we have learnt what are 
+    supported data types, supported operations and operators. How to convert 
+    one data type to other.
 
 *** Notes