Changes made during REC Chennai workshop.

12 files changed, 582 insertions, 53 deletions

diff --git a/day1/day1quiz1.tex b/day1/day1quiz1.tex
index d0da0dd..ee1fe83 100644
--- a/day1/day1quiz1.tex
+++ b/day1/day1quiz1.tex
@@ -58,4 +58,162 @@ On the top right hand corner please write down the following:
   \end{itemize}
 \end{frame}
 
+\begin{frame}[fragile]
+\frametitle{\incqno }
+Draw (roughly) the plot obtained by the following:
+\begin{lstlisting}
+In []: x = linspace(0, 2*pi, 3)
+In []: plot(x, sin(x))
+\end{lstlisting}
+\end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% Describe the plot produced by the following:
+%% \begin{lstlisting}
+%% In []: x = linspace(0, 2*pi, 50)
+%% In []: plot(x, cos(x), 'go')
+%% \end{lstlisting}
+%% \end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+How will you plot the previous graph with line width set to 3?  How will
+you set the $x$ and $y$ labels of the plot?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+How will you set the x and y axis limits so that the region of interest
+is in the rectangle $(0, -1.5)$ (left bottom coordinate) and $(2\pi,
+1.5)$ (right top coordinate)?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+What ipython magic command do you use to obtain the lines of code you have already typed in the interpreter? What command do you use to save them?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+The following code snippet has an error/bug:
+\begin{lstlisting}
+In []: y = linspace(0, 2*pi, 50)
+In []: plot(y, sin(y))
+In []: clf()
+In []: plot(y, cos(y))
+In []: legend(['sin(y)', 'cos(y)']) 
+\end{lstlisting}
+What is the error? How do you fix it?  
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+  \begin{lstlisting}
+  In []: a = [1, 2, 5, 9]
+  In []: a[0:-1]
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+  How do you combine two lists \emph{a} and \emph{b} to produce one list?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+  \begin{lstlisting}
+  In []: a = [1, 2, 5, 9]
+  \end{lstlisting}
+  How do you add the value 10 to the end of this list?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+Write the code to read a file \texttt{data.txt} and print each line of it?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+What would be the result of the following code snippet:
+\begin{lstlisting}
+In []: x = linspace(0, 10, 50)
+In []: y = linspace(50, 100, 100)
+In []: plot(x, y)
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+The following code snippet has an error/bug:
+\begin{lstlisting}
+In []: l = [0.1, 0.2, 0.3, 0.4]
+In []: t = [0.69, 0.90, 1.19, 1.30]
+In []: tsq = []
+In []: for time in t:
+ ....:     tsq.append(time*time)
+ ....:     plot(l, tsq)
+\end{lstlisting}
+What is the error? How do you fix it?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+  A sample line from a Comma Separated Values (CSV) file:\\
+  \vspace*{0.2in}
+  \emph{Rossum, Guido, 42, 56, 34, 54}\\
+  \vspace*{0.2in}
+  What code would you use to separate the line into fields?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+  \begin{lstlisting}
+  In []: a = [1, 2, 5, 9]
+  \end{lstlisting}
+  How do you find the length of this list?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+  \begin{lstlisting}
+  In [1]: d = {
+          'a': 1,
+          'b': 2
+          }
+  In [2]: print d['c']
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+In []: sc = {'A': 10, 'B': 20, 
+             'C': 70}
+\end{lstlisting}
+Given the above dictionary, what command will you give to plot a
+pie-chart?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+In []: marks = [10, 20, 30, 50, 55, 
+                75, 83] 
+\end{lstlisting}
+Given the above marks, how will you calculate the \alert{mean} and
+\alert{standard deviation}?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+In []: marks = [10, 20, 30, 50, 55, 
+               75, 83] 
+\end{lstlisting}
+How will you convert the list \texttt{marks} to an \alert{array}?
+\end{frame}
+
 \end{document}
diff --git a/day1/day1quiz2.tex b/day1/day1quiz2.tex
index 05ab609..539e1e5 100644
--- a/day1/day1quiz2.tex
+++ b/day1/day1quiz2.tex
@@ -61,6 +61,232 @@ On the top right hand corner please write down the following:
   \end{itemize}
 \end{frame}
 
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+In []: a = array([[1, 2],
+                  [3, 4]])
+In []: a[1,0] = 0
+\end{lstlisting}
+What is the resulting array?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+  In []: x = array(([1,2,3,4],
+                    [2,3,4,5]))
+  In []: x[-2][-3] = 4
+  In []: print x
+\end{lstlisting}
+What will be printed?
+\end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% \begin{lstlisting}
+%%   In []: x = array([[1,2,3,4],
+%%                     [3,4,2,5]])
+%% \end{lstlisting}
+%% What is the \lstinline+shape+ of this array?
+%% \end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+  In []: x = array([[1,2,3,4]])
+\end{lstlisting}
+How to change \lstinline+x+ to \lstinline+array([[1,2,0,4]])+?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+  In []: x = array([[1,2,3,4],
+                    [3,4,2,5]])
+\end{lstlisting}
+How do you get the following slice of \lstinline+x+?
+\begin{lstlisting}
+array([[2,3],
+       [4,2]])
+\end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+  In []: x = array([[9,18,27],
+                    [30,60,90],
+                    [14,7,1]])
+\end{lstlisting}
+What is the output of \lstinline+x[::3,::3]+
+\end{frame}
+
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+In []: a = array([[1, 2],
+                  [3, 4]])
+\end{lstlisting}
+How do you get the transpose of this array?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
+In []: a = array([[1, 2],
+                  [3, 4]])
+In []: b = array([[1, 1],
+                  [2, 2]])
+In []: a*b
+\end{lstlisting}
+What does this produce?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+What command do you use to find the inverse of a matrix and its
+eigenvalues?
+\end{frame}
+
+%% \begin{frame}
+%% \frametitle{\incqno }
+%% The file \lstinline+datafile.txt+ contains 3 columns of data.  What
+%% command will you use to read the entire data file into an array?
+%% \end{frame}
+
+%% \begin{frame}
+%% \frametitle{\incqno }
+%% If the contents of the file \lstinline+datafile.txt+ is read into an
+%% $N\times3$ array called \lstinline+data+, how would you obtain the third
+%% column of this data?
+%% \end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+Given a 4x4 matrix \texttt{A} and a 4-vector \texttt{b}, what command do
+you use to solve for the equation \\
+\texttt{Ax = b}?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+What command will you use if you wish to integrate a system of ODEs?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+How do you calculate the roots of the polynomial, $y = 1 + 6x + 8x^2 +
+x^3$?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+Two arrays \lstinline+a+ and \lstinline+b+ are numerically almost equal, what command
+do you use to check if this is true?
+\end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% \begin{lstlisting}
+%%   In []: x = arange(0, 1, 0.25)
+%%   In []: print x
+%% \end{lstlisting}
+%% What will be printed?
+%% \end{frame}
+
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% \begin{lstlisting}
+%% from scipy.integrate import quad
+%% def f(x):
+%%     res = x*cos(x)
+%% quad(f, 0, 1)
+%% \end{lstlisting}
+%% What changes will you make to the above code to make it work?
+%% \end{frame}
+
+%% \begin{frame}
+%% \frametitle{\incqno }
+%% What two commands will you use to create and evaluate a spline given
+%% some data?
+%% \end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% What would be the result?
+%% \begin{lstlisting}
+%%   In []: x
+%%   array([[0, 1, 2],
+%%          [3, 4, 5],
+%%          [6, 7, 8]])
+%%   In []: x[::-1,:]
+%% \end{lstlisting}
+%% Hint:
+%% \begin{lstlisting}
+%%   In []: x = arange(9)
+%%   In []: x[::-1]
+%%   array([8, 7, 6, 5, 4, 3, 2, 1, 0])
+%% \end{lstlisting}
+%% \end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% What would be the result?
+%% \begin{lstlisting}
+%%   In []: y = arange(3)
+%%   In []: x = linspace(0,3,3)
+%%   In []: x-y
+%% \end{lstlisting}
+%% \end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% \begin{lstlisting}
+%%   In []: x
+%%   array([[ 0, 1, 2, 3],
+%%          [ 4, 5, 6, 7],
+%%          [ 8, 9, 10, 11],
+%%          [12, 13, 14, 15]])
+%% \end{lstlisting}
+%% How will you get the following \lstinline+x+?
+%% \begin{lstlisting}
+%%   array([[ 5, 7],
+%%          [ 9, 11]])
+%% \end{lstlisting}
+%% \end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% What would be the output?
+%% \begin{lstlisting}
+%%   In []: y = arange(4)
+%%   In []: x = array(([1,2,3,2],[1,3,6,0]))
+%%   In []: x + y
+%% \end{lstlisting}
+%% \end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% \begin{lstlisting}
+%%   In []: line = plot(x, sin(x))
+%% \end{lstlisting}
+%% Use the \lstinline+set_linewidth+ method to set width of \lstinline+line+ to 2.
+%% \end{frame}
+
+%% \begin{frame}[fragile]
+%% \frametitle{\incqno }
+%% What would be the output?
+%% \begin{lstlisting}
+%%   In []: x = arange(9)
+%%   In []: y = arange(9.)
+%%   In []: x == y
+%% \end{lstlisting}
+%% \end{frame}
+
+
 \end{document}
 
 
diff --git a/day1/exercise/aliquot.py b/day1/exercise/aliquot.py
index 96ea916..25518f0 100644
--- a/day1/exercise/aliquot.py
+++ b/day1/exercise/aliquot.py
@@ -1,18 +1,13 @@
-def is_perfect_square(n):
-    i = 1
-    while i * i < n:
-        i += 1
-    return i * i == n, i
 
 def aliquot(n):
     sum = 1
     i = 2
 
-    is_ps, root = is_perfect_square(n)
-    while i < root:
+    while i * i < n: 
         if n % i == 0:
             sum += i + (n / i)
         i += 1
+    if n % i == 0: sum += i
     return sum
 
 n = int(raw_input('Enter a number? '))
diff --git a/day1/exercise/collatz.py b/day1/exercise/collatz.py
index 2b980d7..7bed967 100644
--- a/day1/exercise/collatz.py
+++ b/day1/exercise/collatz.py
@@ -1,7 +1,10 @@
-a = -1
-while a > 1:
+a = int( raw_input( 'Enter number: ') )
+while a != 4:
     print a
-    if a % 2:
+    if a % 2 == 1:
         a = a * 3 + 1
     else:
         a /= 2
+print 4
+print 2
+print 1
diff --git a/day1/exercise/datestring.py b/day1/exercise/datestring.py
index d990904..4e8cad4 100644
--- a/day1/exercise/datestring.py
+++ b/day1/exercise/datestring.py
@@ -1,23 +1,15 @@
-def get_date_from_str(date_str):
-    month2mm = {
-        'January': 1,
-        'February': 2,
-        'March': 3,
-        'April': 4,
-        'May': 5,
-        'June': 6,
-        'July': 7,
-        'August': 8,
-        'September': 9,
-        'October': 10,
-        'November': 11,
-        'December': 12,
-        }
-
-    dd, month, yyyy = date_str.split()
-
-    mm = month2mm[month]
-    return int(yyyy), int(dd.strip(',')), mm
+month2mm = { 'JAN': 1, 'FEB': 2, 'MAR': 3, 'APR': 4, 'MAY': 5,
+'JUN': 6, 'JUL': 7, 'AUG': 8, 'SEP': 9, 'OCT': 10, 'NOV': 11,
+'DEC': 12 }
 
+COMMA = ','
+SPACE = ' '
 date_str = raw_input('Enter a date string? ')
-print get_date_from_str(date_str)
+date_str = date_str.replace( COMMA, SPACE)
+d, m, y = date_str.split()
+dd = int( d )
+mon = m[:3].upper()
+mm = month2mm[mon]
+yyyy = int( y )
+
+print dd,mm, yyyy
diff --git a/day1/exercise/pytriads.py b/day1/exercise/pytriads.py
index 4c47313..bea543d 100644
--- a/day1/exercise/pytriads.py
+++ b/day1/exercise/pytriads.py
@@ -10,12 +10,8 @@ def gcd(a, b):
     else:
         return gcd(b, a%b)
 
-a = 3
-while a < 100:
-    b = a + 1
-    while b < 100:
-        is_ps, c = is_perfect_square((a * a) + (b * b))
-        if is_ps and gcd(a, b) == 1:
-            print a, b, c
-        b += 1
-    a += 1
+for a in range(3, 501):
+    for b in range( a+1, 501, 2):
+        if gcd( a, b ) == 1:
+            is_ps, c = is_perfect_square((a * a) + (b * b))
+            if is_ps: print a, b, c
diff --git a/day1/session1.tex b/day1/session1.tex
index 9805f2e..a0a9595 100644
--- a/day1/session1.tex
+++ b/day1/session1.tex
@@ -562,7 +562,7 @@ is in the rectangle $(0, -1.5)$ (left bottom coordinate) and $(2\pi,
 What ipython magic command do you use to obtain the lines of code you have already typed in the interpreter? What command do you use to save them?
 \end{frame}
 
-\begin{frame}
+\begin{frame}[fragile]
 \frametitle{\incqno }
 The following code snippet has an error/bug:
 \begin{lstlisting}
diff --git a/day1/session4.tex b/day1/session4.tex
index ddac34a..257fd54 100644
--- a/day1/session4.tex
+++ b/day1/session4.tex
@@ -646,7 +646,7 @@ What will be printed?
 \begin{lstlisting}
   In []: x = array([[1,2,3,4]])
 \end{lstlisting}
-How to \lstinline+x+ to \lstinline+array([[1,2,0,4]])+?
+How to change \lstinline+x+ to \lstinline+array([[1,2,0,4]])+?
 \end{frame}
 
 \begin{frame}[fragile]
@@ -665,6 +665,17 @@ array([[2,3],
 \begin{frame}[fragile]
 \frametitle{\incqno }
 \begin{lstlisting}
+  In []: x = array([[9,18,27],
+                    [30,60,90],
+                    [14,7,1]])
+\end{lstlisting}
+What is the output of \lstinline+x[::3,::3]+
+\end{frame}
+
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+\begin{lstlisting}
 In []: a = array([[1, 2],
                   [3, 4]])
 \end{lstlisting}
diff --git a/day2/cheatsheet3.tex b/day2/cheatsheet3.tex
index 03da579..97cd2ed 100644
--- a/day2/cheatsheet3.tex
+++ b/day2/cheatsheet3.tex
@@ -105,7 +105,7 @@ bye bye vattam
 \section{Self contained python script}
 Functions like \typ{plot}, \typ{linspace} etc are not inbuilt functions. One have to import them to use them.
   \begin{lstlisting}
-from pylab import linspace, pi, sin
+from scipy import linspace, pi, sin
 from pylab import plot, legend, annotate
 from pylab import xlim, ylim
 
diff --git a/day2/day2quiz.tex b/day2/day2quiz.tex
index badefbc..5561d3d 100755
--- a/day2/day2quiz.tex
+++ b/day2/day2quiz.tex
@@ -60,5 +60,127 @@ On the top right hand corner please write down the following:
   \end{itemize}
 \end{frame}
 
+\begin{frame}
+\frametitle{\incqno }
+  What is the largest integer value that can be represented natively by Python?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+  What is the result of 17.0 / 2?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+  Which of the following is not a type in Python?
+  \begin{enumerate}
+    \item int
+    \item float
+    \item char
+    \item string
+  \end{enumerate}
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+How do you create a complex number with real part 2 and imaginary part
+0.5.
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+  What is the difference between \kwrd{print} \emph{x} and \kwrd{print} \emph{x,} ?
+\end{frame}
+
+\begin{frame}
+\frametitle{\incqno }
+  What does '*' * 40 produce?
+\end{frame}
+
+\begin{frame}[fragile]
+\frametitle{\incqno }
+    What is the output of:
+    \begin{lstlisting}
+In []: ', '.join(['a', 'b', 'c'])
+    \end{lstlisting}
+\end{frame}
+
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+In []: 47 % 3 
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}
+    \frametitle{\incqno}
+  How do you find the presence of an element \emph{x} in the list \emph{a}?
+\end{frame}
+
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+In []: set([1, 2, 8, 2, 13, 8, 9])
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+In []: a = {'a': 1, 'b': 2} 
+In []: a['a'] = 10
+pIn []: print a
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+In []: for i in range(3, 10, 2):
+  ...:     print i
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+In []: a = [1, 2, 3] 
+In []: a.extend([5, 6])
+  \end{lstlisting}
+  What is the value of a?
+\end{frame}
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+In []: a = (1, 2, 3)
+In []: a[1] = 10
+  \end{lstlisting}
+  What is the result?
+\end{frame}
+
+\begin{frame}[fragile]
+    \frametitle{\incqno}
+  \begin{lstlisting}
+def func(x, y=10):
+    print x+1, y+10
+
+func(1)
+
+  \end{lstlisting}
+  What is the output?
+\end{frame}
+
+\begin{frame}
+    \frametitle{\incqno}
+  How many items can a function return?
+\end{frame}
+
 \end{document}
 
diff --git a/day2/session3.tex b/day2/session3.tex
index 8e08271..8b2a12f 100644
--- a/day2/session3.tex
+++ b/day2/session3.tex
@@ -250,6 +250,23 @@ NameError: name 'linspace' is not defined
 \begin{frame}[fragile]
   \frametitle{Remedy \ldots}
   \begin{lstlisting}
+from scipy import *
+  \end{lstlisting}
+\alert{Now run python four\_plot.py again}
+\end{frame}
+
+\begin{frame}[fragile]
+  \begin{lstlisting}
+Traceback (most recent call last):
+  File "four_plot.py", line 1, in <module>
+    x = plot(x, x, 'b')
+NameError: name 'plot' is not defined
+  \end{lstlisting}
+\end{frame}
+
+\begin{frame}[fragile]
+  \frametitle{Remedy \ldots}
+  \begin{lstlisting}
 from pylab import *
   \end{lstlisting}
 \alert{Now run python four\_plot.py again!!}
@@ -261,8 +278,8 @@ from pylab import *
     \item The \kwrd{import} keyword ``loads'' a module
     \item One can also use:
       \begin{lstlisting}
-In []: from pylab import *
-In []: from pylab import linspace
+In []: from scipy import *
+In []: from scipy import linspace
       \end{lstlisting}    
     \item What is the difference?
     \item \alert{Use the former only in interactive mode}
@@ -282,7 +299,7 @@ from scipy.optimize import fsolve
   \frametitle{\texttt{from} \ldots \texttt{import} - conventional way!}
   \small
   \begin{lstlisting}
-from pylab import linspace, pi, sin
+from scipy import linspace, pi, sin
 from pylab import plot, legend, annotate
 from pylab import xlim, ylim
 
@@ -302,17 +319,18 @@ ylim(-5*pi, 5*pi)
   \frametitle{\texttt{from} \ldots \texttt{import} - conventional way!}
   \small
   \begin{lstlisting}
+import scipy
 import pylab
 
-x = pylab.linspace(-5*pylab.pi, 5*pylab.pi, 500)
+x = scipy.linspace(-5*scipy.pi, 5*scipy.pi, 500)
 pylab.plot(x, x, 'b')
 pylab.plot(x, -x, 'b')
-pylab.plot(x, pylab.sin(x), 'g', linewidth=2)
-pylab.plot(x, x*pylab.sin(x), 'r', linewidth=3)
+pylab.plot(x, scipy.sin(x), 'g', linewidth=2)
+pylab.plot(x, x*scipy.sin(x), 'r', linewidth=3)
 pylab.legend(['x', '-x', 'sin(x)', 'xsin(x)'])
 pylab.annotate('origin', xy = (0, 0))
-pylab.xlim(-5*pylab.pi, 5*pylab.pi)
-pylab.ylim(-5*pylab.pi, 5*pylab.pi)
+pylab.xlim(-5*scipy.pi, 5*scipy.pi)
+pylab.ylim(-5*scipy.pi, 5*scipy.pi)
   \end{lstlisting}
 \end{frame}
 
diff --git a/day2/session5.tex b/day2/session5.tex
index c5809c5..abbd2af 100644
--- a/day2/session5.tex
+++ b/day2/session5.tex
@@ -138,9 +138,17 @@ aliquot(12) = 1 + 2 + 3 + 4 + 6 = 16.\\
 \inctime{10}
 \end{frame}
 
-\begin{frame} 
+
+\begin{frame}
   \frametitle{Problem 3}
-  Count frequencies of words in a file.
+Given a list of words, find all the anagrams in the list.
+Solve the problem without using dictionaries.
+
+\end{frame}
+
+\begin{frame} 
+  \frametitle{Problem 4}
+  Count frequencies of words in a file named 'holmes.txt'.
 \inctime{25}
 \end{frame}