Persistent Realities » Home

Site
News
Files

Visual Basic
Strings
Math
General
Properties
Memory
Methods

Inline ASM-VB
Strings
Math
General
Memory

Division vs Multiplication (update!)

Someone pointed me on the fact that I used a wrong variable type somewhere. I fixed this and tested it again, and this time, the multiplication was faster than division, which was proven otherwise in a previous test.

Declaration: Dim lngReturn As Single Dim Action As Single

Code:
Public Sub TestOne()
    Action = 4
    lngReturn = 10  Action
End Sub

Public Sub TestTwo()
    Action = 0.25
    lngReturn = 10 * Action
End Sub

The variable conversion which was required previously made the multiplication slower.

Div % faster than Mul	Div (sec)	Mul (sec)
304.2%	0.086051	0.021289
182.8%	0.079669	0.028168
269.8%	0.078566	0.021244
192.1%	0.077067	0.026381
261.1%	0.079152	0.02192

User contributed notes:

Author: PRoPHEZZoR (Name_Here_No_Spam at HaCKERMAiL dot COM)	Date: 11:08 24/08/2004
Uhm... When working with automation, wouldn't you (If you wanna use * instead of \\) first divide the Action value with what you would normally multiply by, thus neutralizing the "optimization"? Sorry 4 being a smart-ass, just wanna share some thoughts ;-)
Author: Tom (hurendo_kun at hotmail dot com)	Date: 14:05 31/05/2005
Yes, but this assumes you want to divide in bulk by the same denominator, in which case pre-processing it once and multiplying a million times is generally faster -- but on modern FPU's it doesn't really matter.