Math issue?

[David A. Osborn]

I'm doing the below calculating in VB.net. All variable are declared as
double and their contents are below.


mdblMidtermWt 0.2 Double
mdblFinalWt 0.2 Double
mdblAssignWt 0.2 Double
mdblGroupWt 0.3 Double
mdblPartWt 0.1 Double

temp 1.0000000000000002 Double


temp = mdblMidtermWt + mdblFinalWt + mdblAssignWt + mdblGroupWt + mdblPartWt

Last I check 0.2 + 0.2 + 0.2+0.3 + 0.1 was equal to 1 so why am I getting
1.0000000000000002 ?

 

[Herfried K. Wagner [MVP]]

temp = mdblMidtermWt + mdblFinalWt + mdblAssignWt + mdblGroupWt +
mdblPartWt

Last I check 0.2 + 0.2 + 0.2+0.3 + 0.1 was equal to 1 so why am I getting
1.0000000000000002 ?

That's a characteristic of floating point numbers.

<URL:http://research.microsoft.com/~hollasch/cgindex/coding/ieeefloat.html>
<URL:http://www.math.grin.edu/~stone/courses/fundamentals/IEEE-reals.html>
<URL:http://support.microsoft.com/?scid=kb;[LN];42980>

 

[m.posseth]

use the decimal dataype