VB.Net Significant Figure Rounding

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Can anyone give me a VB.net equivalent to the below Excel Formula:

number = 1.234567
=ROUND(number, 4-(INT(LOG(number)+1)))

This example returns 1.235 to 4 sig figs.

Posted 28-Jan-13 2:49am

mccrimmon

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Sergey Alexandrovich Kryukov 28-Jan-13 12:00pm

Why do you think you need rounding? It is almost never used. Maybe you need just the string presentation with less digits? This is a different story.
—SA

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CPallini · Answer 1 · 2013-01-28T03:33:00

Solution 1

VB

Math.Round(number, 4 - (CType(Math.Log10(number) + 1, Integer)))

Posted 28-Jan-13 3:33am

CPallini

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Kschuler 28-Jan-13 14:41pm

Be careful with Math.Round. You may need to also specify a second parm to specify how to round when a number is half way to the next integral....See here: http://msdn.microsoft.com/en-us/library/as4h66hd(v=vs.90).aspx
Which states "By default, Math.Round uses MidpointRounding.ToEven. Most people are not familiar with "rounding to even" as the alternative, "rounding away from zero" is more commonly taught in school. .NET defaults to "Rounding to even" as it is statistically superior because it doesn't share the tendency of "rounding away from zero" to round up slightly more often than it rounds down (assuming the numbers being rounded tend to be positive.) "

CPallini 28-Jan-13 15:31pm

I know that.

Kschuler 28-Jan-13 15:32pm

:) I just meant it would be nice to warn the OP.

CPallini 28-Jan-13 15:48pm

I know that. :-)

Member 9451274 12-Feb-15 2:43am

This gave me a error in some combinations.

http://stackoverflow.com/questions/202302/rounding-to-an-arbitrary-number-of-significant-digits - and Pyrolistical answer