System.Numerics.BigInteger.Log10

前々から、BigInteger.Log10 が使えなくて、何でだろうと思ってたんですが、

c:\>fsi

Microsoft (R) F# 2.0 Interactive build 2.0.0.0
Copyright (c) Microsoft Corporation. All Rights Reserved.

For help type #help;;

> System.Numerics.BigInteger.Log10 10I;;

  System.Numerics.BigInteger.Log10 10I;;
  ---------------------------^^^^^

c:\stdin(1,28): error FS0039: The field, constructor or member 'Log10' is not defined
> #q;;

単にパスが通ってないというお粗末なお話でした...

c:\>"C:\Program Files\FSharp-2.0.0.0\v4.0\bin\fsi"

Microsoft (R) F# 2.0 Interactive build 4.0.40219.1
Copyright (c) Microsoft Corporation. All Rights Reserved.

For help type #help;;

> System.Numerics.BigInteger.Log10 10I;;
val it : float = 1.0
> #q;;