It there a way in powershell to make a positive number to a negative number whitout using multiplication?

Question

I was wondering if there is a way to make a positive number into a negative number whitout using a multiplication like $b = $a * -1
I'm looking for the most cost sensible way because I'm gonna do this a lot of times in a script.

-edit At this point I'm using this, but lookes very costly computation wise:

    $temp_array = New-Object 'object[,]' $this.row,$this.col

    for ($i=0;$i -le $this.row -1 ; $i++) {
        for ($j=0;$j -le $this.col -1 ; $j++) {
            $digit = $this.data[$i,$j] * -1
            $temp_array[$i,$j] = 1 / ( 1 + [math]::exp( $digit ) )
            #[math]::Round( $digit ,3)
        }
    }
    $this.data = $temp_array

Answer 1

To unconditionally turn a positive number into its negative equivalent (or, more generally, flip a number's sign), simply use the unary - operator:

 PS> $v = 10; -$v
 -10

Applied to your case:

 $digit = -$this.data[$i,$j]

---

As an aside: If performance matters, you can speed up your loops by using .., the range operator to create the indices to iterate over, albeit at the expense of memory consumption:

$temp_array = New-Object 'object[,]' $this.row,$this.col

for ($i in 0..($this.row-1)) {
    for ($j in 0..($this.col-1)) {
        $digit = - $this.data[$i,$j]
        $temp_array[$i,$j] = 1 / ( 1 + [math]::exp( $digit ) )
    }
}
$this.data = $temp_array