# Exercise 1

## 1 Array Indexing

In the class ArrayIndexing below you should first define a 2x3-array and set values to every position in the array. Also define a second array while you're at it, with the same size but with different values. The last thing you should do is to change a few values in each array. Then you're done!

Oh, one more thing, what are the results after changing the values?

### 1.1 Tip

When you set the values in the arrays you can use the fill function to fill a whole array with a value. fill(value, nrOfRows, nrOfColumns).

### 1.2

#### 1.2.1 array1

the result of array2 {{10, 1, 1}, {23, 1, 1}}

#### 1.2.2 array2

the result of array2 {{1, 1, 1}, {100, 100, 100}}

## 2 Indexing with Scalar Expressions

In the class ArrayIndexing2 below you should first define a 2x2-array and set values to every position in the array. Then define a second 2x4-array with different values. This time you should change a whole row in each array.

What are the results after changing the values?

### 2.1

#### 2.1.2 array1

the result of array1 is {{9, 9}, {2, 20}}

#### 2.1.3 array2

the result of array2 {{7, 7, 7, 7}, {6, 7, 8, 9}}

## 3 Accessing Array Slices with Index Vectors

What is the result of the vectors v1, v2, v3, v4, v5, v6, v7, v8 and v9 below?

### 3.1

#### 3.1.1 v1

v1 gets the value {22, 33, 44}.

#### 3.1.2 v2

v2 gets the third row of V, i.e. the vector {44, 11, 77}.

#### 3.1.3 v3

v3 gets the second element (in brackets) in the third row in V, i.e. {11}.

#### 3.1.4 v4

v4 gets the second row of W, i.e. {13, 88, 43}

#### 3.1.5 v5

v5 gets the first and second elements of Y, i.e. {23, 24}

#### 3.1.6 v6

v6 gets the first and second elements on the third row of W, i.e. {99, 43}

#### 3.1.7 v7

v7 gets the first and second elements of the third row of V, i.e. {44, 11, 77}

#### 3.1.8 v8

v8 gets the 3:rd through 4:th elements of Y as {25, 26}

#### 3.1.9 v9

v9 gets the 1:st to 5:th elements step 2 elements as {23, 25, 27}