PowerShell Double Type

last modified February 15, 2025

This tutorial explains PowerShell's double type, a 64-bit floating-point numeric data type used for decimal calculations. Doubles provide precision for scientific and financial operations while handling large value ranges.

The double type (System.Double) stores numbers with decimal points in IEEE 754 format. PowerShell automatically interprets numbers with decimals as doubles, but explicit typing ensures data consistency in scripts.

Declaring Double Variables

PowerShell infers numeric types based on values. Assign decimals to create doubles automatically:

basic_double.ps1

$pi = 3.1415926535
[double]$gravity = 9.80665

Write-Output "Pi: $pi"
Write-Output "Gravity: $gravity"

This script demonstrates implicit and explicit double declarations. Both variables store 64-bit floating-point values.

$pi = 3.1415926535

PowerShell automatically assigns the double type when using decimal values.

[double]$gravity = 9.80665

Explicit typing ensures the variable remains a double even if assigned whole numbers later.

Arithmetic Operations

Doubles support standard arithmetic operations. Be mindful of precision limitations in complex calculations:

operations.ps1

$radius = 5.5
$area = [math]::PI * ($radius * $radius)
Write-Output "Circle area: $area"

This calculates a circle's area using the Math.PI constant. Note the result's precision extends to 15 decimal places.

Precision Considerations

Double precision can lead to rounding errors in sensitive calculations:

precision.ps1

$sum = 0.1 + 0.2
$comparison = $sum -eq 0.3
Write-Output "0.1 + 0.2 equals 0.3? $comparison"

Due to binary representation, this comparison returns False. Use decimal type for exact precision in financial calculations.

Type Conversion

Convert between numeric types using casting or parsing:

conversion.ps1

$stringValue = "123.45"
$doubleFromString = [double]::Parse($stringValue)
$intToDouble = [double]42

Write-Output "Parsed: $doubleFromString"
Write-Output "Integer to double: $intToDouble"

This demonstrates safe conversion from string and integer types to double.

Formatting Double Output

Control decimal display using format strings:

formatting.ps1

$temperature = 23.56789
Write-Output ("Formatted: {0:N2}°C" -f $temperature)
Write-Output ("Scientific: {0:E3}" -f $temperature)

The format operator (-f) specifies decimal places and scientific notation.

Source

Microsoft Double Type Documentation

This tutorial covered essential double type operations in PowerShell. For precision-critical applications, consider the decimal type. Always test floating-point logic thoroughly.

Author

Jan Bodnar is a software developer and technical writer with extensive experience in system programming and scripting languages. Author of multiple programming books and maintainer of the ZetCode tutorial platform.

List all PowerShell tutorials.

Ebooks