Android Question How use comparation <= operator in float?

[Paolo Pini]

What is it that I didn't understand?

    Dim Value As Float=8.21
    Log(Value <=8.20)    'FALSE'
    Log(Value <=8.21)    'FALSE'?
    Log(Value <=8.22)    'TRUE'

 

[aeric]

Log(Value)                        ' 8.210000038146973
Log(Round2(Value, 2) <= 8.21)     ' TRUE

 

[Paolo Pini]

Log(Value)                        ' 8.210000038146973
Log(Round2(Value, 2) <= 8.21)     ' TRUE

I see, thank you!

 

[aeric]

Not sure why you want to use Float.
I think it is better to use Double.

 

[Paolo Pini]

Not sure why you want to use Float.
I think it is better to use Double.

I agree, for my calculations, Double is sufficent. ?

 

[Erel]

I don't like Round2. Both Float and Double cannot 100% accurately represent all values. Using BigDecimal from BigNumber library is one option.

Another one is to use a method such as this one:

Public Sub AreEqual(d1 As Double, d2 As Double) As Boolean
 Return Abs(d1 - d2) < 0.000001
End Sub

If value1 < value2 Or AreEqual(value1, value2) Then
 ...

 

[ilan]

this works too:

    Dim Value As Float=8.21
    Log(NumberFormat2(Value,1,2,0,False) <=8.20)    'FALSE'
    Log(NumberFormat2(Value,1,2,0,False) <=8.21)    'TRUE'
    Log(NumberFormat2(Value,1,2,0,False) <=8.22)    'TRUE'

 

[Erel]

This is quite hacky. NumberFormat returns a string which is them implicitly parsed to a number. The only reason that it works is that the implicit parsing returns a double which is the same type of the right hand side. I wouldn't consider it safe code.

The correct way to compare two floating point numbers for equality is by dealing with the expected inaccuracy.

 

[Daestrum]

Or make the comparison valid

    Dim Value As Float=8.21
    Log(Value <= (8.20).As(Float))    'FALSE'
    Log(Value <= (8.21).As(Float))    'TRUE'
    Log(Value <= (8.22).As(Float))    'TRUE'