How can we find sum of diagonal matrix using powershell

Question

How can we find sum of diagonal matrix using powershell

Narasimha 61

Sum of diagonal matrix in power shell

Accepted answer

4 additional answers

Your answer

Answer 1

Michael Taylor 60,161

PS is basically .NET so any .NET solution will work. For example here's one I googled real quick.

$sum = 0
$matrix = @(@(1, 2, 3, 4), @(5, 6, 7, 8), @(1, 2, 3, 4), @(5, 6, 7, 8))
for ($i = 0; $i -lt $matrix.length; ++$i) { 
   $sum += [double]$matrix[$i][$i]                                                                                     
}

Answer 2

Do you want the Principal or Secondary sum? Or both?

Function DiagonalSums{
    [CmdletBinding()]
    param (
        [Parameter()]
        [int[,]]
        $matrix,

        [Parameter()]
        [int]
        $n              # order of the matrix
    )    
    [int]$principal = 0
    [int]$secondary = 0

    For ($i = 0; $i -lt $n; $i++) {
        $principal += $matrix[$i,$i]
        $secondary += $matrix[$i,($n - $i - 1)]
    }
    [PSCustomObject]@{
        Principal = $principal
        Secondary = $secondary
    }   
}

# Driver code

#
# test data
#

# Principal diagonal = 18, Secondary diagonal = 18
#$elements = 1,2,3,4,5,6,7,8,1,2,3,4,5,6,7,8
#$n = 4     # order of the matrix

# Principal diagonal = 16, Secondary diagonal = 20
#$elements = 1,2,3,4,4,3,2,1,7,8,9,6,6,5,4,3
#$n=4        # order of the matrix

# Principal diagonal = 3, Secondary diagonal = 3
$elements = 1,1,1,1,1,1,1,1,1
$n = 3      # order of the matrix

$mat = New-Object "int[,]" $n,$n

# load the matrix
$e = 0
For ($i = 0; $i -lt $n; $i++){
    For ($j = 0; $j -lt $n; $j++){
            $mat[$i,$j] = $elements[$e]
            $e++
    }
}

DiagonalSums $mat $n

Narasimha 61 Reputation points

2021-07-20T04:53:35.337+00:00

values should be given by user

Answer 3

Anonymous

Hi,

Do you mean the sum of the diagonal elements (the trace) of the diagonal matrix?

$matrix = @((1,0,0,0),(0,2,0,0),(0,0,3,0),(0,0,0,4))  
$sum = 0  
for($i=0;$i -lt $matrix.count;$i++){  
    $sum += $matrix[$i][$i]      
}  
$sum

Best Regards,
Ian Xue

============================================

If the Answer is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Narasimha 61 Reputation points

2021-07-20T04:54:08.597+00:00

values should be given by user

Anonymous

Do you want to input the matrix from the console？

[int]$order = Read-Host "Input the order of the matrix"
[array[]]$matrix = [array[]]::new($order)
for($i=1;$i -le $order;$i++){
    $matrix[$i-1] = (Read-Host "Input Row $i").Split(',')    
}
$sum = 0
for($i=0;$i -lt $matrix.count;$i++){
    $sum += $matrix[$i][$i]    
}
$sum

The elements are separated by ",".

Answer 4

Narasimha 61

iam trying to give values at runtime but while doing diagonal matrix it throwing error as cannot index into null value array

Michael Taylor 60,161 Reputation points

2021-07-20T13:18:11.23+00:00

You need to add the elements to the array as you get them from the user. If you know the size in advance (say 4x4) then pre-create the array and then just fill it in otherwise start with an empty array and add elements using the += operator. Of course the user will need to identify the rows so they could either enter each row's values or enter a special value to indicate end of row. It is up to you.

The hardest part about all this is that PS tries to be smart with arrays so if you store your row values into an array and then attempt to add that to the matrix using += it'll add the individual elements, not the array itself.

Answer 5

If you want the user to enter the data you have only to use the function I gave you to calculate the result but instead of using the method I used (loading from a file), substitute this instead:

$n = Read-Host "Enter the order of the matrix: "
$mat = New-Object "int[,]" $n,$n
Write-Host "Enter the values, one value at a time, row-by-row:"
For ($i = 0; $i -lt $n; $i++){
    For ($j = 0; $j -lt $n; $j++){
            $mat[$i,$j] = Read-Host "Enter value: "
    }
}

I'm also curious to know if this is some sort of homework assignment!

Share via

How can we find sum of diagonal matrix using powershell

4 additional answers

Your answer