godarda@gd:~$ R
...
Matrix creation
> matrix1 = matrix(1:9,nrow = 3,ncol = 3)
> matrix2 = matrix(1:9,nrow = 3,ncol = 3)

Addition
> matrix3 = matrix1 + matrix2
> matrix3
     [,1] [,2] [,3]
[1,]    2    8   14
[2,]    4   10   16
[3,]    6   12   18

Subtraction
> matrix3 = matrix1 - matrix2
> matrix3
     [,1] [,2] [,3]
[1,]    0    0    0
[2,]    0    0    0
[3,]    0    0    0

Division
> matrix3 = matrix1 / matrix2
> matrix3
     [,1] [,2] [,3]
[1,]    1    1    1
[2,]    1    1    1
[3,]    1    1    1

Multiplication
> matrix3 = matrix1 %*% matrix2
> matrix3
     [,1] [,2] [,3]
[1,]   30   66  102
[2,]   36   81  126
[3,]   42   96  150

Transpose of a matrix
> matrix2
     [,1] [,2] [,3]
[1,]    1    4    7
[2,]    2    5    8
[3,]    3    6    9

> matrix3 = t(matrix2)
> matrix3
     [,1] [,2] [,3]
[1,]    1    2    3
[2,]    4    5    6
[3,]    7    8    9

> matrix3[3,3]
[1] 9

> matrix3[1,2]
[1] 2

Substitution of a number
> matrix3[1,1] = 100
> matrix3
     [,1] [,2] [,3]
[1,]  100    2    3
[2,]    4    5    6
[3,]    7    8    9

> matrix3[,2] = 100
> matrix3
     [,1] [,2] [,3]
[1,]  100  100    3
[2,]    4  100    6
[3,]    7  100    9

> matrix3[,2:3] = 24
> matrix3
     [,1] [,2] [,3]
[1,]  100   24   24
[2,]    4   24   24
[3,]    7   24   24

Matrix with four rows
> matrix(c(1,2,3,4,5,6,7,8,9,10,11,12),nrow = 4)
     [,1] [,2] [,3]
[1,]    1    5    9
[2,]    2    6   10
[3,]    3    7   11
[4,]    4    8   12

Matrix with three rows and four columns
> matrix(c(1,2,3,4,5,6,7,8,9,10,11,12),nrow = 3,ncol = 4)
     [,1] [,2] [,3] [,4]
[1,]    1    4    7   10
[2,]    2    5    8   11
[3,]    3    6    9   12

> matrix(1:50,ncol = 10)
     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]    1    6   11   16   21   26   31   36   41    46
[2,]    2    7   12   17   22   27   32   37   42    47
[3,]    3    8   13   18   23   28   33   38   43    48
[4,]    4    9   14   19   24   29   34   39   44    49
[5,]    5   10   15   20   25   30   35   40   45    50

> matrix(1:50,ncol = 10) + 100
     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]  101  106  111  116  121  126  131  136  141   146
[2,]  102  107  112  117  122  127  132  137  142   147
[3,]  103  108  113  118  123  128  133  138  143   148
[4,]  104  109  114  119  124  129  134  139  144   149
[5,]  105  110  115  120  125  130  135  140  145   150