Modern Math ScaleB

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ScaleB

Multiplies a number by a power of two exactly, by adjusting its exponent.

Syntax

ScaleB( byval x as float64, byval n as int32 ) as float64

Notes

• x * 2 ^ n computed by adjusting the exponent, so it is exact and cannot lose precision the way multiplying by a computed power can.
• It also survives an intermediate that would overflow: 2 ^ 1000 is an infinity, but scaling by 1000 and back is not.
• The inverse partner of Frexp.

Examples

#import "std/numeric"
using numeric

print ScaleB( 1.0, 10 )      '' 1024
print ScaleB( 3.0, -1 )      '' 1.5

'' Exact, and no intermediate to overflow
print ScaleB( ScaleB( 1.0, 1000 ), -1000 )    '' 1

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Library: Math Library
Category: Math Library
Documented under: Members