Self-Assessment

Use the exercises and questions below to check that you have the required basic MATLAB knowledge to continue with the rest of the course.

Creating vectors and matrices

Input the following vectors and matrices into MATLAB. Are there multiple commands that you can use to create these objects?

A = \begin{bmatrix} 4 & 9 & 3\\ 1 & 0 & 0\\ 3 & -4.5 & 9 \end{bmatrix}\hspace{20pt} B = \begin{bmatrix} 4.5 & 0 & 0\\ 0 & 2 & 0\\ 0 & 0 & 3 \end{bmatrix}\hspace{20pt} b = \begin{bmatrix} 11\\ -9\\ 3 \end{bmatrix}\hspace{20pt} c = \begin{bmatrix} 5.5 & 0 & -5 \end{bmatrix}

Which command would you use to...

...access the element containing $1$ in matrix $A$ ?
...replace the $-4.5$ element in matrix $A$ with an $8$ ?
...to create a vector that contains the main diagonal of matrix $B$ ?
...to create the following matrix by using vector $b$ ? $C = \begin{bmatrix} 11 & 11 & 11\\ -9 & -9 & -9\\ 3 & 3 & 3 \end{bmatrix}$
...to create a $9 \times 1$ column vector that contains the elements of matrix $A$ columnwise?
...to create a $9 \times 1$ column vector that contains the elements of matrix $A$ rowwise?
... to divide all elements of matrix $B$ by 2?
... to add matrix $A$ and $B$ elementwise?
... to divide matrix $A$ by $B$ elementwise?
... to invert matrix $B$ ?
... to create a $9 \times 9$ identity matrix?
... to create a column vector of 30 linearly spaced numbers from 10 to 110?
... to create a $3\times 7$ matrix of zeros?
... to extract the second column of $A$
... to extract the third row of $B$
... to select the lower right $2 \times 2$ matrix in matrix $A$ ?
... to create a column vector that is the sum of the columns of $A$
... to calculate the columnwise mean of $B$ ?
... to get the minimal element of $A$ ?
... to get the maximal element of each column of $A$ ?
... to get the maximal element of each row of $A$ ?

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