How to solve this bug?

Question

1.00/5 (1 vote)

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Hi,

Does anyone know how to solve the following in vb.net 2013 ?

VB

Dim x1 As Double = -0.3
Dim x2 As Double = 0.7
Dim xx As Double = x1 ^ x2 '=-1.#IND
xx = Math.Pow(x1, x2)      '=-1.#IND
xx = -0.3 ^ 0.7            '= -0.43051162024993422
xx = Math.Pow(-0.3, 0.7)   '=-1.#IND

Thanks

Posted 19-Jun-15 4:23am

vdw

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2 solutions

Solution 1

There is no bug. The ^ operator is not for performing exponent operations. This operator is an exclusive-or operator. Please see the documentation:
^ Operator[^]

Posted 19-Jun-15 4:36am

virusstorm

Comments

F-ES Sitecore 19-Jun-15 10:43am

That's true for c# but not for VB.net :)

https://msdn.microsoft.com/en-us/library/zh100ckf.aspx

OriginalGriff 19-Jun-15 10:43am

Reason fro my vote of one: ^ is XOR in C#.
In VB it's "To The Power Of":
https://msdn.microsoft.com/en-us/library/b6ex274z.aspx

Thomas Daniels 19-Jun-15 10:44am

That's true for C# but not for VB.NET, and the OP's problem is in VB.NET.
https://msdn.microsoft.com/en-us/library/zh100ckf.aspx

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OriginalGriff · Accepted Answer · 2015-06-19T04:41:00

Solution 2

If you look at the definition of Math.Pow[^] it says:

txt

x < 0 but not NegativeInfinity; y is not an integer, NegativeInfinity, or PositiveInfinity.
Returns NaN

So try:

VB

xx = Math.Sign(x1) * Math.Pow(Math.Abs(x1), x2)

Posted 19-Jun-15 4:41am

OriginalGriff

Comments

vdw 19-Jun-15 10:54am

Thanks, this solved it !

OriginalGriff 19-Jun-15 11:03am

You're welcome!