diff --git a/404.html b/404.html new file mode 100644 index 0000000..086a5c9 --- /dev/null +++ b/404.html @@ -0,0 +1,25 @@ +--- +permalink: /404.html +layout: default +--- + + + +
Page not found :(
+The requested page could not be found.
+Page not found :(
+The requested page could not be found.
+We will soon be composing an introduction for this initiaitve. \(a^2\) $b^45$
+ +**Where do I start from? **
+ +This page will soon be updated.
+ +_posts
directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve
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+
+Jekyll requires blog post files to be named according to the following format:
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Where YEAR
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+ +All is well
]]>_posts
directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve
, which launches a web server and auto-regenerates your site when a file is updated.
+
+Jekyll requires blog post files to be named according to the following format:
+ +YEAR-MONTH-DAY-title.MARKUP
Where YEAR
is a four-digit number, MONTH
and DAY
are both two-digit numbers, and MARKUP
is the file extension representing the format used in the file. After that, include the necessary front matter. Take a look at the source for this post to get an idea about how it works.
Jekyll also offers powerful support for code snippets:
+ + + +Check out the Jekyll docs for more info on how to get the most out of Jekyll. File all bugs/feature requests at Jekyll’s GitHub repo. If you have questions, you can ask them on Jekyll Talk.
+ +All is well
]]>Either don’t preach, or practice what you preach :-)
]]>Coming soon.
+ + +This is a first course in mathematics with emphasis on helping a learner with a bunch of tools and techniques required for studying several aspects of data sciences. We will illustrate the ideas through questions and puzzles. We would like to replace theorems with intuition and give pointers to inspired students to look up material for further study. By the end of the course, the student will be confident on the basics of linear algebra and probability. The course will end with a couple of exemplary ideas in data sciences and the importance of the math thus studied.
+ +An important aspect of any course that is heavy on math, is to develop confidence to read up abstract material. The symbolc manipulation and logical reasoning are toolkits to infer unambiguously. It helps to stay confident and continuously interact with peers/TAs/Professor. Expect the material to be hard on your minds to begin with, but one will surely feel comfortable with time. An important tip is to take a relook at a mathematical concept multiple times, asking what is the question for which the concept is an answer. It helps to solve questions that challenge your conceptual understanding than solve multiple problems of similar type.
+ +There will be performance points assigned to every student using the following rule:
+ ++ | + |
---|---|
Attendance in classes/labs | +2 per hour | +
Late for the class/lab (irrespective of the urgency) | +-10 per class/lab | +
Plagiarism/Cheating/Misconduct | +PP will drop to 0 | +
Challenge Assignment | +X | +
Final grades will be calculated based on the following rule: +\(\left(\frac{PP}{100}.Total\right)+\left( \frac{PP}{8}\right)\)
+ +Where PP stands for Performance Points and Total is the marks secured from theory, lab and project components.
+ +Evaluation
+ +Type | ++ | Marks | +
---|---|---|
Theory Internals | +Involves theory related grading: quiz and written assignments | +10 | +
Theory Externals | +Final Theory Exam | +35 | +
Lab Internals | +Grading based on lab performance and viva voce | +10 | +
Lab Externals | +Final Lab Exam | +35 | +
Final Project | ++ | 10 | +
Theory assignments will involve writeups that are mostly straight forward and will be indicative of the difficulty in the mid term and final exams. Questions for the final exam will be consequential concepts from the assignments. It would help if assignments are taken seriously for the student to secure good marks in the exams.
+ +Lab assignments will involve you to work on programming based questions. These can be take home tests or in lab tests. The difficulty level is indicative of the final lab exam questions. The evaluation of lab assignments will involve a strong viva voce component.
+ +The student will be asked to pick a project from a list of topics. The projects will mostly be explorative in nature. Every project will be executed by a team of at most 2 people. Evaluation of the project will be based on the report and presentation.
+ +This is a homepage for the members of Coder’s High group. Check the FAQ if you are here for the first time. Check the Oceanverse and get started with your learning.
+ +We are currently discussing Matrices
+ + + + + +We encounter equations very often in our lives. Consider for example, the following situation at Baker’s Cafe. The manager has a very important estimate to make. Mostly, visitors at his cafe happen to be families and they are often comprised of Children and/or Adults. He observes that there are 3 adults and 1 child at a table and their bill turns out to be Rs.1200/-. There is yet another table with 2 children and 1 adult and their bill comes out to be Rs.1000/-. Can the manager estimate the consumption of a Child/Adult? This is popularly called the Simultaneous Equations and we all remember from our school days, multiple ways in which these can be solved.
+\(3A + 1C = 1200\)
+\(1A + 2C = 1000\)
While we were taught the so called two variables and two unknowns, what if there were more equations than unknowns?
+\(3A + 1C = 1200\)
+\(1A + 2C = 1000\)
+\(1A + 1C = 900\)
Note that the previous question can be modelled as a matrix:
+ +\(3A + 1C = 1200\)
+\(1A + 2C = 1000\)
+\(1A + 1C = 900\)
Observe this is same as :
+ +\(\left( \begin{matrix} 3 & 1 \\1 & 2 \\1 & 1 \\\end{matrix}\right)\) +\(\left( +\begin{matrix} +B\\ +C\\ +\end{matrix} +\right)\) += +\(\left( + \begin{matrix} + 1200\\ + 1000\\ + 900\\ + \end{matrix} +\right)\)
+The best way to solve is, is to guess the values :-). Can you write a python code to guess the values?
+How do you solve this mathematically? There are two nice ways of solving this:
+Define a function. What is a surjective, injective and bijective +function?
+Given an example of a function +\(f:\mathbb{R}^2\rightarrow\mathbb{R}^2\)
+Given a function \(\phi : \mathbb{R}^2 \rightarrow \mathbb{R}^2\) +which satisfies the following two conditions:
+ +\[\phi(u+v)=\phi(u) +\phi(v)\] + +\[\phi(\alpha v)=\alpha\phi(v)\] + +Consider \(\mathbb{R}^2\) what are all the properties of this set? +\(\mathbb{R}^2\) is called a space of all vectors, aka a vector space. +Lookup for the definition of a vector space.
+A subset of a vector space which in itself is a vector space is +caled a subspace. Given an example of a subspace of \(\mathbb{R}^2\).
+Given a vector \((1,7)\) what does the set +\(\{ \alpha(1,7) | \alpha \in \mathbb{R}\}\) represent? Is it a +subspace of \(\mathbb{R}^2\)?
+Is \(\mathbb{R}^3\) a vector space?
+Conside the two points \((1,2,3)\) and \((4,5,7)\in \mathbb{R}^3\). What +does the following set denote: +\(\{\alpha(1,2,3)+\beta(4,5,7) | \alpha, \beta \in \mathbb{R}\}\). +Is this a subspace?
+Consider a straight line \(y=2x+1\) in \(\mathbb{R}^2\), does it form a +subspace of \(\mathbb{R}^2\)?
+Consider a unit circle in \(\mathbb{R}^2\), centered at origin, is it +a subspace of \(\mathbb{R}^2\)?
+What are all the subspaces of \(\mathbb{R}^2\)?
+What are all the subspaces of \(\mathbb{R}^3\)?
+Given \(\mathbb{R}^3\), pick any two points \(u,v\in \mathbb{R}^3\). +Note that \(\{\alpha u+\beta v | \alpha, \beta \in \mathbb{R}\}\) is a +subspace of \(\mathbb{R}^3\). Generalize this idea!
+The set \(\{\alpha u + \beta v | \alpha, \beta \in \mathbb{R}\}\) is +called the linear combination of vectors \(u\) and \(v\). We can +generalize this to \(k\) vectors. Observe what this set is all about?
+We say that a vector \(w\) is manufactured by \(u\) and \(v\) if +\(w\in \{\alpha u +\beta v | \alpha, \beta \in \mathbb{R} \}\).
+Show that \((1,2,3)\) and \((4,5,6)\) can manufacture \((7,8,9)\). Also +\((4,5,6)\) and \((7,8,9)\) can manufacture \((1,2,3)\). Finally \((4,5,6)\) +can be manufactured by the other two vectors.
+Can \((2,1,0)\) and \((3,0,8)\) manufacture \((1,1,1)\) ?
+Can \((0,0,1)\) and \((0,1,0)\) manufacture \((1,0,0)\)?
+When can two vectors in \(\mathbb{R}^3\) manufacture a given third +vector?
+When can two vectors in \(\mathbb{R}^3\) fail to manufacture a given +third vector?
+If \(\{u,v,w\}\) are such that a vector in this set can be +manufactured by some vectors in the same set, then such a set is +called a linearly dependent set.
+Give examples of a linearly dependent set in \(\mathbb{R}^3\) and get +conversant with the definition.
+If \(\{u,v,w\}\) are such that no vector in this set can be +manufactured by any combination of vectors in the same set, then such +a set is called a linearly independent set.
+Give examples of a linearly dependent set in \(\mathbb{R}^3\) and +\(\mathbb{R}^2\) and get conversant with the definition.
+Are \((1,2), (3,4)\) linearly independent in \(\mathbb{R}^2\)? Prove!
+Are \((1,1),(2,3),(7,17)\) Linearly Independent or Dependent?
+Construct a set of 3 vectors that are Linearly Independent in +\(\mathbb{R}^2\). Can you?
+Construct a set of 3 vectors that are Linearly Independent in +\(\mathbb{R}^3\). Can you?
+Construct a set of \(k\) vectors that are Linearly Independent in +\(\mathbb{R}^k\). Can you?
+Construct a set of \(k+1\) vectors that are Linearly Independent in +\(\mathbb{R}^k\). Can you?
+Show that in \(\mathbb{R}^2\) we can at most have 2 Linearly +Independent vectors.
+Show that in \(\mathbb{R}^3\) we can at most have 3 Linearly +Independent vectors.
+Show that in \(\mathbb{R}^n\) we can at most have \(n\) Linearly +Independent vectors.
+Set of any two linearly independent vectors in \(\mathbb{R}^2\) is +called a basis. Set of any three linearly independent vectors in +\(\mathbb{R}^3\) is called a basis. Similarly, for \(n\).
+Show that a basis can manufacture any vector of the vector +space.
+Show that any set of linearly independent vectors form a subset of +some basis. In other words, one can include a few more elements to a +linearly independent set and make it a basis.
+Show that the number of elements in any basis for a given vector +space is always constant.
+Try taking a few vectors in \(\mathbb{R}^3\) and discuss its linear +independence or linear dependence. Try atleast 10 examples and +familiarize yourself.
+Show that any 3 vectors on a plane passing through the origin in +\(\mathbb{R}^3\) cannot be linearly independent. Prove.
+What are all the subspaces of \(R^3\).
+Consider a subspace of \(R^3\) and write down its basis. Do this for 3 +to 4 different subspaces.
+Give an example of a function +\(f:\mathbb{R}^2 \rightarrow \mathbb{R}^2\) such that the range of the +function is the straight line \(y=10x\).
+As an example consider the following basis set of +\(\mathbb{R}^2 : \left \{(1,2),(2,2)\right \}\). Construct a function +\(\phi:\mathbb{R}^2\rightarrow \mathbb{R}^2\) such that:
+ +\[\phi(u+v)=\phi(u)+\phi(v)\] + +\[\phi(\alpha u)= \alpha \phi(u)\] + +Such a function is called a LT function,
+ +Where is (1,2) and (2,2) mapped?
+Where is (1,0) and (0,1) mapped?
+What is the range of this function?
+Consider a function \(\phi\) which is LT which maps
+ +\[\phi(1,2)=(3,4)\] + +\[\phi(6,6)= (2,0)\] + +How many such functions can you construct?
+What is the range of this function?
+Discuss the range of the following functions, given their values at +a few points:
+ +\(\phi(1,2)=(3,4)\) \(\&\) \(\phi(1,1)=(6,8)\)
+ +\(\phi(1,1)=(2,2)\) \(\&\) \(\phi(3,3)=(4,4)\)
+ +\(\phi(1,2)=(3,5)\) \(\&\) \(\phi(0,8)=(3,0)\)
+ +\(\phi(-2,2)=(0,0)\) \(\&\) \(\phi(8,2)=(1,1)\)
+ +\(\phi(1,1)=(2,2)\) \(\&\) \(\phi(1,2)=(3,3)\)
+Give an example of an LT function which maps a L.I. set of vectors +to a L.I. set of vectors i.e. +\(\phi:\mathbb{R}^2 \rightarrow \mathbb{R}^2\), where +\(\left \{ u,v \right \}\) are L.I. \(\&\) +\(\left \{\phi(u), \phi(v)\right \}\) are also L.I.
+Same as the previous question, but \(\left \{ u,v \right \}\) is L.I.
+and \(\left \{\phi(u), \phi(v)\right \}\) is L.D.
+What can one say about the range?
Note that range of a L.I function is always a subspace.
+Note that the set N=\(\{v: \phi(v)=0\}\) is a subspace of \(R^2\) where +\(\phi:\mathbb{R}^2\rightarrow \mathbb{R}^2\) is L.I . Take atleast 5 +different examples of L.I functions and see if this is true. The set +\(N\subseteq Domain\) is called the null space of \(\phi\).
+Construct a Linear Transformation +\(\phi:\mathbb{R}^2\rightarrow \mathbb{R}^2\), +\(\phi(0,1)=(3,4)\) and \(\phi(1,0)=(1,2)\). Construct an inverse of +linear transformation and observe it carefully. Is it a L.T function +too?
+Do you realize the importance of inverting a matrix?
+L.T stands for Linear Transformation .It is aka a matrix.
+Define a L.T. \(\phi:\mathbb{R}^2\rightarrow \mathbb{R}^2\) such that
+\(\phi(0,1)=(2,3)\) and \(\phi(1,0)=(7,4)\). This function \(\phi\) is same
+as the matrix \(\begin{bmatrix}
+7 & 2 \\
+4 & 3
+\end{bmatrix}\).
+
\(\phi(x,y)\) is same as \(\begin{bmatrix}
+7 & 2 \\
+4 & 3
+\end{bmatrix}\) \(\begin{bmatrix}
+x\\y
+\end{bmatrix}\), Verify and make your share of observations.
+What is
+\(\phi^{-1}\) ? Is this the traditional matrix inverse?
+
Think !
Consider a L.T. \(\phi\) such that : \(\phi(1,2)=(3,5)\) and +\(\phi(3,1)=(8,2)\). What is the matrix equivalent of \(\phi\) ?
+Isn’t this the same as \(\begin{bmatrix} +1 & -2 \\ +1 & 4 +\end{bmatrix}\) \(\begin{bmatrix} +x\\y +\end{bmatrix}\) = \(\begin{bmatrix} +15\\19 +\end{bmatrix}\)
+You are trying to find if there is an element in the domain +which maps to (15,19) .
+Given \(V_{1}\) , \(V_{2}\) & \(V_{3}\) are L.I. , S.T.
+ +\(\left \{ V_{2} - V_{3} , V_{1} - V_{3} , V_{1} - V_{2} \right \}\) +are L.D.
+\(\left \{ V_{1} + V_{2} , V_{1} + V_{3} , V_{2} + V_{3} \right \}\) +are L.I.
+Given vectors \(\left \{ V_{1} , V_{2} , V_{3} , V_{4} \right \}\) +their sum is 0 = \(V_{1}\) + \(V_{2}\) + \(V_{3}\) + \(V_{4}\) . Is this set +L.I or L.D. ?
+Show that the following are equivalent:
+ +The vectors \(\{v_1,v_2,\dots, v_n\}\) are linearly independent.
\(\forall \alpha_1, \alpha_2, \dots, \alpha_n \in \mathbb{R}\ \left( \sum_{i=1}^{n} \alpha_i v_i = 0 \implies \alpha_j = 0\ \forall 1 \leq j \leq n\right)\).
In the following six matrices find out the following:
+ +Rank of the matrix
+Dimension of the range
+ +What is happening here? Describe in detail.
+The dimension of the range of the matrix \(M\) and \(M^{T}\) is always +the same. Why?
+Take three linearly independent vectors in \(\mathbb{R}^3\). Show that +they form a basis of \(\mathbb{R}^3\).
+Consider the matrix \(\left[ \begin{array}{ccc} +1 & 4 & 7\\ 2 & 5 & 8 \\ 3 & 6 & 9 +\end{array}\right]\). The dimension of the range is 2. The range of +this linear transformation is obviously a linear combination of +three vectors. Do you see which are those three vectors?
+Consider any \(2 \times 2\) matrix. Do you observe that the :
+ +Dimension of the Null space & the Dimension of the range are in someway related?
+What about a \(3 \times 3\) matrix?
+Can you generalise this to an \(n\times n\) matrix?
+When is a L.T. function one-one and when is it onto?
+A \(2\times 2\) matrix A can be seen as two vectors placed as columns. For +example \((1,2)\) and \((3,4)\) when placed as columns give rise to the +matrix \(\begin{bmatrix} +1 & 3 \\ +2 & 4 +\end{bmatrix}\).
+ +Note that \(\begin{bmatrix} +1 & 3 \\ +2 & 4 +\end{bmatrix}\) \(\begin{bmatrix} +\alpha \\ +\beta +\end{bmatrix}\) \(\in\) +\({\{ \alpha(1,2)+\beta(3,4) : \alpha, \beta \in \mathbb{R} \} }\).
+ +Note that matrix, \(\begin{bmatrix} +a & b \\ +c & d +\end{bmatrix}\) \(\begin{bmatrix} +x \\ +y +\end{bmatrix}\) simply is \(x(a,c)+y(b,d)\).
+ +Note that a matrix takes a vector \((x,y)\) to a linear combination of +the column vectors.
+ +It is now clear that the range of the matrix, say\(\begin{bmatrix} +1 & 1 & 4 \\ +0 & 2 & 4 \\ +1 & 3 & 4 +\end{bmatrix}\) is nothing but the linear combination of the vectors +\((1,0,1), (1,2,3), (4,4,4)\).
+Consider a \(10\times 10\) matrix \(A\), defined as following:
+ +\(A[i,j] = 0\) if \(i+j\cong 0(mod2)\)
+ +\(A[i,j] = 1\) if \(i+j\cong 1(mod2)\)
+ +What is the dimension of the range?
+Consider the sub-space \(S:(y=13x)\) of \(\mathbb{R}^2\)
+ +Give an example of a \(\phi\) such that \(S\) is its null space.
+Give an example of a \(\phi\) such that S is the the + range of \(\phi\).
+Let \(A =\) +\(\begin{bmatrix} +1 & 3 \\ +2 & 4 +\end{bmatrix}\)
+ +Show that the null space of \(A \subset\) Null space of \(A^2\)
+Is this true for any \(2\times 2\) matrix.
+Is this true for any \(3\times3\) matrix.
+Is this true for any \(n\times n\) matrix.
+Define column space. S.T. Column space of \(A^2 \subset\) Column space +of \(A\).
+What does one mean by the linear combination of vectors and what is a +linear span?
+Show that, if a matrix \(A\) has linearly independent column vectors, +then the columns of the matrix \(A^2\) are also linearly independent.
+\(Ax = Ay \iff x=y\) . Is this true? If False, when is the statement +False and what leads to the falsity of the statement?
+Let \(M\) be a \(3\times 3\) matrix, such that, the dim(Range) =3. Show +that, \(M^2 = M \iff M\) is an identity matrix.
+Watch these videos without fail. This is a good intuitive introduction to linear algebra.
+These Videos make an essential introduction to calculus.
+Here is a complete course on linear algebra from MIT OCW. It is the most popular resource for the subject.
+Ram and Lakshman were two brothers, Ram’s pocket money was twice as much as Lakshman. The good boy that Ram and Lakshman were, they did not spend their pocket money on anything. They instead saved the same in their piggy bank. Every week, they would check their savings so far. Assume the first week’s savings was \((R_1,L_1)\) and second week’s \((R_2,L_2)\) and so on. They try plotting their weekly savings on a graph sheet. How will the points look like?
+Atul’s house is centered at origin \((0,0)\) he walks straight (along the x-axis) for 2 units and then takes a left and walks 1 unit to reach Bala’s house, after that he takes a right turn and walks for one unit and then a left turn and walks for one unit and reaches Chetan’s house. He continues in a similar style, takes a right turn 1 unit and then left turn one unit and reaches Divya’s house. Are the houses of Bala, Chetan and Divya on a straight line? What is the equation of this line? Plot this on Geogebra
+Plot the lines \(y=x\), \(y=2x\), \(y=10x\).
+Observe that they all pass through the origin. Why?
+Plot \(y=2x+1\). Why doesn’t it pass through the origin?
+Plot \(y=ax+b\), with \(a\) and \(b\) as parameters which you should be able to varry. What do youaa observe?
+Consider the following simultaneous equation:
+ +\(2x+3y=7\)
+\(3x+4y=10\)
Do you see a 2x2 matrix here? What is the importance of seeing a matrix in this problem? Why study matrices in general?
Do you observe that this problem can be retold as:
\(\left( \begin{matrix} 2 & 3 \\3 & 4 \\\end{matrix}\right)\)
+\(\left(
+\begin{matrix}
+x\\
+y\\
+\end{matrix}
+\right)\)
+=\(\left(
+\begin{matrix}
+7\\
+10\\
+\end{matrix}
+\right)\)
Consider a simple function \(f(x) = 3x+2\). This function is invertible right? Can you tell us what is \(\alpha\) such that \(f(\alpha)=17\)? Is such an \(\alpha\) unique? How did you find such an \(\alpha?\). Is this always possible?
+Consider the function \(f(x)=x^2-10\), what is f(5)?
+Consider the function \(f(x)=x^2-10\), if \(f(\alpha)=54\), what is \(\alpha\)?
+Consider the function \(g(x)=x^3-x^2-10x+2\), if \(g(x)=-22\) what is \(x\)?
+Do you know what is \(\mathbb{R}, \mathbb{R}^2 and \mathbb{R}^3\) ?
+Consider the function \(\phi : \mathbb{R}^2\rightarrow \mathbb{R}^2\) defined by \(\phi (x,y)=(2x+3y,3x+4y)\). What has this to do with the previous question?
+Is the function \(\phi\) invertible? In the question above on matrices, we see that it is of the form \(Ax=b\). Note that we can invert the matrix, using the method that was taught to us in our high school to find out the value for the variables x and y. This is one of the many applications of matrices.
+We will now see matrices as functions. Instead of \(\phi\) we will write the matrix itself:
\(\left( \begin{matrix} 2 & 3 \\3 & 4 \\\end{matrix}\right) : \mathbb{R}^2 \rightarrow \mathbb{R}^2\).
Consider the function \(\left( \begin{matrix} 1 & 2 \\2 & 4 \\\end{matrix}\right) : \mathbb{R}^2 \rightarrow \mathbb{R}^2\). This matrix takes a few elements to the origin. What are those elements? Plot this using Geogebra.
+We encounter equations very often in our lives. Consider for example, the following situation at Baker’s Cafe. The manager has a very important estimate to make. Mostly, visitors at his cafe happen to be families and they are often comprised of Children and/or Adults. He observes that there are 3 adults and 1 child at a table and their bill turns out to be Rs.1200/-. There is yet another table with 2 children and 1 adult and their bill comes out to be Rs.1000/-. Can the manager estimate the consumption of a Child/Adult? This is popularly called the Simultaneous Equations and we all remember from our school days, multiple ways in which these can be solved.
+\(3A + 1C = 1200\)
+\(1A + 2C = 1000\)
While we were taught the so called two variables and two unknowns, what if there were more equations than unknowns?
+\(3A + 1C = 1200\)
+\(1A + 2C = 1000\)
+\(1A + 1C = 900\)
Note that the previous question can be modelled as a matrix:
+ +\(3A + 1C = 1200\)
+\(1A + 2C = 1000\)
+\(1A + 1C = 900\)
Observe this is same as :
+ +\(\left( \begin{matrix} 3 & 1 \\1 & 2 \\1 & 1 \\\end{matrix}\right)\) +\(\left( +\begin{matrix} +A\\ +C\\ +\end{matrix} +\right)\) += +\(\left( + \begin{matrix} + 1200\\ + 1000\\ + 900\\ + \end{matrix} +\right)\)
+One obvious way to solve this, is to guess the values :-). Can you get closer to the solution by guessing? Note that there is no solution to this question. You can just reduce the error. Do you see why?
+In the figure below: + +If 1000 people were to start in one state, what will be the distribution of people eventually?
+Use Geogebra: +Draw the vector \(\begin{bmatrix}1 \\ +1 \\ +\end{bmatrix}\). Find out all those vectors which are perpendicular to this vector.
+Do you observe that we are asking for vectors \(\begin{bmatrix}x \\ +y \\ +\end{bmatrix}\) such that, +\(\begin{bmatrix}x & y \\ +\end{bmatrix} \begin{bmatrix} 1\\ 1 \\ \end{bmatrix}=0\)
+Use Geogebra and solve the above question with \(\begin{bmatrix} 1 \\ +1 \\ +\end{bmatrix}\) replaced by \(\begin{bmatrix}a \\ +b \\ +\end{bmatrix}\).Use \((a,b)\) as parameters and check what happens to \((x,y)\).
+What is \((x,y,z)\) satisfying the following equation? (Use Geogebra) +\(\begin{bmatrix}x & y & z\\ +\end{bmatrix} \begin{bmatrix} 1\\ 2 \\ 3\\ \end{bmatrix}=0\)
+Use Geogebra and plot all the points in the set below. +\(T= \{ \beta(1,2,1) | \beta \in \mathbb{R}\}\)
+Use Geogebra and plot all the points in the set below. +\(S= \{ \beta(2,7.3) | \beta \in \mathbb{R}\}\)
+Use Geogebra and plot all the points in the set below. +\(W= \{\alpha(1,2,1) + \beta(2,7.3) | \alpha,\beta \in \mathbb{R}\}\)
+In the above set W find out all the points satisfying \((x,y,z)\) satisfying the following: (Use Geogebra) +\(\begin{bmatrix}w1 & w2 & w3\\ +\end{bmatrix} \begin{bmatrix} x\\ y \\ z\\ \end{bmatrix}=0\) + where \((w1,w2,w3) \in \mathbb W\)
+Given the matrix \(A=\begin{bmatrix}1 & 2 & 3\\ 4 & 5 &6\\ 7 & 8 & 9\\ \end{bmatrix}\), find out all the possible \((x,y,z)\) such that: +\(\begin{bmatrix}1 & 2 & 3\\ 4 & 5 &6\\ 7 & 8 & 9\\ \end{bmatrix} \begin{bmatrix} x\\ y\\ z\\ \end{bmatrix}=0\) + Observe carefully, what has this question got to do with previous five questions in this module
+Given the matrix \(A=\begin{bmatrix}1 & 2 & 3\\ 4 & 5 &6\\ 7 & 8 & 9\\ \end{bmatrix}\) what does the following three sets represent?
+(i) \(\mathscr{R}=\{\alpha(1,2,3) + \beta(4,5,6) + \gamma(7,8,9) |\alpha, \beta, \gamma\in \mathbb{R}\}\)
+(ii) \(C=\{\alpha(1,4,7) + \beta(2,5,8) + \gamma(3,6,9) | \alpha, \beta, \gamma \in \mathbb{R}\}\)
+(iii) \(N=\{(x,y,z)|x(1,4,7) + y(2,5,8) + z(3,6,9) = 0 \}\)
+ Use only Geogebra :)
Did you observe that every vector of \(\mathscr{R}\) is perpendicular to every vector of \(N\)?
+Consider the matrix \(B=\begin{bmatrix} 1 & 2 \\ 2 & 4\\ \end{bmatrix}\). Draw the line \(2y+x=4\). Seeing the matrix \(B\) as a function \(B:\mathbb{R^2}\mapsto \mathbb{R^2}\),
where does \(B\) takes the line \(2y+x=4\)?
+Where does it take:
+i)\(2y+x=10\)
+ii)\(2y+x=62\)
+iii)\(2y+x=1800\)
In general \(B=\begin{bmatrix} 1 & 2 \\ 2 & 4\\ \end{bmatrix}:\mathbb{R^2}\mapsto \mathbb{R^2}\), where does this function take \(2y+x=k\)?(where \(k\) is a constant)
+Given \(B=\begin{bmatrix} 1 & 2 \\ 2 & 4\\ \end{bmatrix}:\mathbb{R^2}\mapsto \mathbb{R^2}\). What is the range of this function?
+You have achieved the required wisdom if you have realized that:
+\(B=\begin{bmatrix} 1 & 2 \\ 2 & 4\\ \end{bmatrix}:\mathbb{R^2}\mapsto \mathbb{R^2}\).
Given the matrix \(M=\begin{bmatrix} 1 & 3 \\ 2 & 6\\ \end{bmatrix}\). Use Geogebra to plot \(\mathscr{R}\), \(\mathscr{C}\) & \(\mathscr{N}\). what do you observe?
+(i) \(\mathscr{R}=\{\alpha(1,3) + \beta(2,6) | \alpha, \beta\in \mathbb{R}\}\)
+(ii) \(\mathscr{C}=\{\alpha(1,2) + \beta(3,6) | \alpha, \beta\in \mathbb{R}\}\)
+(iii) \(\mathscr{N}=\{(x,y)| x(1,3) + y(2,6) = 0, \forall x,y\in \mathbb{R} \}\)
Note that \(\mathscr{R}\) and \(\mathscr{N}\) are orthogonal.
What is the null-space of \(M=\begin{bmatrix} 1 & 3 \\ 2 & 6\\ \end{bmatrix}\) & the null-space of \(M^T\)?
Do you observe that \(C(M)\) ⊥ \(N(M^T)\) \(R(M)\) ⊥ \(N(M^T)\) ?
Consider \(A=\begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \\ \end{bmatrix}\). What is \(N(A)\), \(C(A)\), \(R(A)\), \(N(A^T)\).
Consider a 4x4 matrix \(M\): \(\mathbb{R^4}\mapsto \mathbb{R^4}\) whose range is
+a) \(4-Dimension\)
+b) \(3-Dimension\)
+c) \(2-Dimension\)
+d) \(1-Dimension\)
+e) \(0-Dimension\)
+Give an example each for all the above 5 cases.
Consider \(A : \mathbb{R^{3}} \to \mathbb{R^{3}}\)
+a) S.T. if the range contains a point \((a,b,c)\), then it should contain the entire set $S$, defined by:
+\(S= \{\alpha(a, b,c)/ \alpha \in \mathbb{R}\}\).
+b) S.T. if the range contains the points \((a,b,c)\) and \((d,e,f)\), then the range contains the entire set \(T\) defined by:
+\(T=\{\alpha(a,b,c) + \beta(d,e,f) \thinspace/\thinspace \alpha,\beta\in \mathbb{R}\}\).
+c) Note: \(S\) is of the dimension \(1\), but \(T\) need’nt be of dimension \(2\). Think!
1) Give an example of two $2-dim$ subspaces in $\mathbb{R^{3}}$. Let us call it $S_1, S_2$
+ +2) Let $S_3$ be all those vectors perpendicular to $S_1$. $S_4$ be that of $S_2$
+ +3)Find a matrix M whose Null-Space is $S_3$. column space is $S_2$
+ +4)What does $S_1$ $S_4$ represent
+ +5) Do you observe there is a bijection from $S_1 \to S_4$
+ +1. Write a program that prints “Namasthey India” to the screen (1 point).
+ +2. Take as input a number \(n\) and print the square, cube and \(2^n\) of the number (1 point).
+ +3. Print the following using four print statements:
+*
+**
+***
+****
+
(1 point) .
+ +4. Write an interactive python program which does the following:
+What's your name? John
+How old are you? 25
+What's your favorite color? Blue
+What's your favorite hobby? Reading
+
(1 point).
+ +5. Understand how to use a if conditional
in python. Ask the user to enter a number and check if the number is even or odd (1 point).
6. Write a program to take as input a number \(n\) and display the first \(n\) natural numbers (1 point).
+ +7. Print a sequence of numbers starting from the number a with common difference d. Go on till you reach the number b.
+Enter a value for a: 10
+Enter a value for d: 3
+Enter a value for b: 20
+Output: 10 13 16 19
+
(1 point).
+ +8. Write a program that calculates and prints the sum of all numbers from 1 to n, where n is provided by the user (1 point).
+ +9. Write a program that takes a number n from the user and prints the multiplication table for that number from 1 to 10. Generalize it from \(i\) to \(j\).
+2X1=2
+2X2=4
+and so on...
+
(1 point).
+ +10. Write a program to find out if the given number is prime or not (1 point).
+ +11. Write a program to take as input \(n\) and print all prime numbers upto and including \(n\) (1 point).
+ +12. Input two different strings and concatenate it (1 point).
+ +13. Take two strings of the same length and intersperse the second one into the first one:
+Input:
+india
+super
+Output:
+isnudpiear
+
(1 point).
+ +14. Given a string, write a program to reverse it (1 point).
+ +15. Given a string, check if it is a palindrome or not (1 point).
+ +16. Write a program that counts and prints the number of vowels and the number of consonants in the string (1 point).
+ +17. List of Squares: Write a program that prints the square of numbers from 1 to n, where n is provided by the user (1 point).
+ +18. Fibonacci Sequence : Write a program that prints the first n numbers in Fibonacci numbers (1 point).
+ +19. Print Star Pattern: Write a program that takes a number n from the user and prints a right-angled triangle pattern with stars of n rows (1 point) .
+ +20. Write a piece of code which does exactly as specified in this video (10 points).
+ +21. Factorial: Write a program that calculates the factorial of a number provided by the user (1 point).
+ +22. Positive or Negative: Write a program that asks the user for a number and prints whether the number is positive, negative, or zero (1 point).
+ +23. Simple Interest Calculation: Write a program that calculates the simple interest for given principal, rate, and time provided by the user (1 point).
+ +24. Temperature Converter: Write a program that converts Celsius to Fahrenheit or Fahrenheit to Celsius, depending on user input (1 point).
+ +25. Leap Year or Not: Write a program that checks if a given year is a leap year or not. Google for the details on how to figure out if the given number is a leap year or not. It is more complicated than simply checking for a multiple of 4 (1 point).
+ +26. Divisible by 7 and 5: Write a program that checks if a number provided by the user is divisible by both 7 and 5. Generalize it to a and b (1 point).
+ +27. Create a Python program that prompts the user for their age. If the age is less than 18, print “You are a minor.” If the age is between 18 and 65, print “You are an adult.” Otherwise, print “You are a senior citizen.” (1 point).
+ +28. Grading System: Write a program that takes the marks of five subjects from the user and calculates the grade according to the average marks: +A if average >= 90 +B if average >= 80 and < 90 +C if average >= 70 and < 80 +D if average >= 60 and < 70 +F otherwise +(1 point).
+ +29. Decimal to Binary Conversion: Write a program that converts a decimal number to its binary representation using loops, without using built-in conversion functions (1 point).
+ +30. Write a program that finds the gcd of two numbers using Euclid’s Algrorithm. Given \(k\) as an input, display those two numbers, both with \(k\) digits, such that they take the maximum number of steps to find the GCD, across all the pair of numbers, both of which are of \(k\) digits (8 points).
+ +31. Write a program to populate a list \(L\) with the first \(n\) natural numbers (1 point).
+ +32. Write a program to populate a list \(L\) with random numbers in the range 1 to 1000 (1 point).
+ +(Watch these videos, as and when required)
+ +33. Write a function called add
that takes two numbers as arguments and returns their sum. (1 point)
34. Write a function called factorial
that takes an integer n
and returns the factorial of n
. (1 point)
35. Write a function called fibonacci
that takes an integer n
and returns the n
-th number in the Fibonacci sequence. (1 point)
36. Write a function which simulates the process of throwing \(n\) identical balls into \(n\) bins. What is the maximum across the buckets? Write a short report on the output of your code. (2 points)
+ +37. Write a function which simulates the process of throwing identical balls into \(n\) identical bins until all the bins are non-empty. How many balls are we expected to throw? Investigate and write a short report based on your observation. (2 points)
+ +38. Checking for Even or Odd: Write a function called is_even
that takes an integer and returns True
if the number is even, and False
if it is odd. (1 point)
39. Calculate Area of a Circle: Write a function called circle_area
that takes the radius of a circle as an argument and returns its area. (1 point)
40. Write a function that displays the spiral: RULLDDRRRUUULLLL… and so on. It should keep displaying until it has displayed 1,000,000 Letters in this pattern. (5 points)
+ +41. Concatenating Strings: Write a function called concatenate
that takes two strings and returns them concatenated together with a space between them. (1 point)
42. Finding the Maximum: Write a function called find_max
that takes a list of numbers and returns the largest number in the list. (1 point)
43. Consider the sensex data from here. Consider only the end of the day closing values. When should you have bought and when should you have sold in order to gain the maximum return in this 30 year period? You can assume that you can buy the stocks partially and you start with, let us say 1,00,000 Rupees. (10 points)
+ +44. Consider the data of Height and Weight of 25,000 people as available here. Is the data correlated? What is the correlation? Can you plot the points and fit a line? You are free to use any built in functions, but you should know what the functions are doing. Correlation is a statistical concept which you may know from your high school, we only expect you to understand this concept at an intuitive level. (5 point)
+ +45. Reading exercise (first few chapters of Algorithms to live by). (25 points)
+ +46. Write a function that takes as inputs list of lists that depicts square matrices A and B and then gives us the sum. (1 point)
+ +47. Write a function that takes as inputs list of lists that depicts square matrices A and B and then gives us the product. (2 points)
+ +48. Write a function that writes the first n numbers and writes it to a file by name output.txt (1 point)
+ +49. Write a function that reads a file which has numbers in each line and outputs it on the screen one by one. (1 point)
+ +50. Solve this question. (10 points)
+ +51. Write a program to sort a list of numbers using the bubble sort technique. (1 point)
+ +52. Write a program to sort a list of numbers using the merge sort technique. (2 point)
+ +53. Write a program to sort a list of numbers using the quick sort technique. (2 point)
+ +54. Write a program to search for an element in a list using Binary Search.(2 point)
+ +55. Write a program which, given a text file comprising of all words in lower case, one word per line, sorts this file using bubble sort, merge sort and quick sort. Which technique is the fastest and why? Write a detailed report. (5 points)
+ +56. Write a program to find the median element in a list of unsorted elements. You are not supposed to sort the list. (2 points)
+ +57. Solve the contiguous sum sub array problem (1 point).
+ +58. We solved the SFC question a while ago. Can you solve this on similar lines? (2 points)
+ +59. Write a program to encrypt a string using caesar cipher. (1 point)
+ +60. Read and Solve this (20 points)
+ + +You’ll find this post in your _posts
directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve
, which launches a web server and auto-regenerates your site when a file is updated.
Jekyll requires blog post files to be named according to the following format:
+ +YEAR-MONTH-DAY-title.MARKUP
Where YEAR
is a four-digit number, MONTH
and DAY
are both two-digit numbers, and MARKUP
is the file extension representing the format used in the file. After that, include the necessary front matter. Take a look at the source for this post to get an idea about how it works.
Jekyll also offers powerful support for code snippets:
+ + + +Check out the Jekyll docs for more info on how to get the most out of Jekyll. File all bugs/feature requests at Jekyll’s GitHub repo. If you have questions, you can ask them on Jekyll Talk.
+ +All is well
+ +Consider the previous \(2\times 2\) matrix and find out its eigenvalue and eigenvectors. What do you observe?
+Consider the following network: +Assign values to the nodes so that the value of the nodes = sum of the values of the nodes from which there are incoming edges. For example the value of F should be half of the value of C. The value of E should be half the value of B and so on.
+Write down the edge list of the above graph and use networkx to run a random walk on it. What is the distribution of visits?
+Are the following two questions equivalent?:
+ +If I were to give pocket money to two of my daughters: 500 rupees each.
+I toss a coin and give my elder daughter 1000 rupees if its heads or the younger daughter 1000 rupees if its tails.
+ +Are these two statements equivalent? In the sense that, by the end of the year, do you think both my daughters would have received, more or less, the same amount of money?
+Consider the adjacency matrix of the above graph, tweak it and observe that the principal eigen vector is same as the answer to the previous question. (Principal Eigen Vector is defined as the eigen vector corresponding to the highest eigen value)
+What is the intuition for this infinite series being equal to 1? \(\frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \frac{1}{16} + \dots\)
+Fact: \(\frac{1}{1-x} = 1+x+x^2+x^3+\dots\). Is this always true?
+Note that \(e = 1 + \frac{1}{1!} + \frac{1}{2!} + \frac{1}{3!}\dots\). Why is this number important? Can you notice that this number is obviously greater than 1? Can you show that it is actually less than 3?
+Note that \(e^x = 1 + \frac{x}{1!} + \frac{x^2}{2!} + \frac{x^3}{3!}\dots\). What is the significance of this?
+Understand Binomial Theorem and show that \(\left( 1+\frac{1}{n}\right)^n = e)\)
+If you keep compounding your money, when will it get doubled? (Hint: \(\left( 1+\frac{1}{n}\right)^n = e)\))
+If you keep spending your money by \(\epsilon\) proportion, when will your money get to less than a rupee?
+If you consider a 1000 meter long stick and randomly break it at some point, what do you expect the length to be, of the smaller part and the bigger part?
+A bus conductor charges 1000 rupees per seat. The bus can accommodate 100 people. If \(k\) number of seats are empty, the conductor levies a penalty of \(10k\) on each passenger. For example, if 5 seats are empty, the conductor will charge 1050 for the 95 passengers who are present. What is the number of passengers for which the conductor earns the maximum money?
+Understand the Monty Hall problem.
+What is the importance of a matrix? Where do we use them?
+What is the intuitive idea of an inverse of a matrix?
+In the following code, what is the probability that \(a\), \(b\) and \(c\) form the sides of a triangle?
+ +import random
+a=random.random()
+b=random.random()
+c=random.random()
+
Show that \(sqrt(2)\) is irrational.
+Show that prime numbers are infinite.
+You know the old school way of adding, subtracting, multiplying and dividing 2 big numbers. Can you provide a proof for these methods?
+Find the GCD of two big numbers using only a calculator. What method helps you calculate the GCD fast? How do you know that the method works? Can you figure out the number of steps it takes to arrive at a solution?
+Describe Birthday Paradox. Write a piece of python code to figure out the probability of you finding same birthdays in a class of \(n\) people. Plot the probability on the \(Y\) axis and the number of people in the class \(n\) in the \(X\) axis. How does the curve look like?
+After programmatically understanding the birthday paradox, can you understand it mathematically?
+When you distribute \(n\) chocolates to \(n\) people uniformly at random, many of them may end up getting more than one chocolate. How many people, on an average, end up getting no chocolates at all.
+\((a + b)^n = \sum_{k=0}^{n} \binom{n}{k} a^{n-k} b^k\)
+The following syllabus is only indicative of the topics we will be covering. We may not follow this sequence. The teaching style will be illustrative and not enumerative.
+ +Sl. No. | +Topic | +
---|---|
1 | +Introduction to Mathematical Thinking | +
2 | +A Gentle Introduction to Probability | +
3 | +Random Variables and Expectations | +
4 | +Distributions: Binomial, Bernoulli, Gaussian & Poisson | +
5 | +Markov Chains | +
6 | +Introduction to Matrices | +
7 | +Linearly Independent and Dependent Vectors | +
8 | +Linear Transformations | +
9 | +Matrix Factorization | +
10 | +Applications: Dimensionality Reduction, Recommender Systems, Pagerank, Support Vector Machines | +
@TAs
+ +Note: Leave it to me if you cannot cover some of the topics.
+ +There is a project for 10 marks. Feel free to give them some reading or programming assignment based on the math concepts taught.
+ +Regards,
+Sudarshan
You’ll find this post in your _posts
directory. Go ahead and edit it and re-build the site to see your changes. You can rebuild the site in many different ways, but the most common way is to run jekyll serve
, which launches a web server and auto-regenerates your site when a file is updated.
Jekyll requires blog post files to be named according to the following format:
+ +YEAR-MONTH-DAY-title.MARKUP
Where YEAR
is a four-digit number, MONTH
and DAY
are both two-digit numbers, and MARKUP
is the file extension representing the format used in the file. After that, include the necessary front matter. Take a look at the source for this post to get an idea about how it works.
Jekyll also offers powerful support for code snippets:
+ + + +Check out the Jekyll docs for more info on how to get the most out of Jekyll. File all bugs/feature requests at Jekyll’s GitHub repo. If you have questions, you can ask them on Jekyll Talk.
+ +All is well
+ +