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type "does not support numeric operations"
f#

I am trying to use my own custom record type as a value in a Math.Matrix.Generic matrix. It evaluates ok however when I run it it throws this exception:

"System.NotSupportedException: The element type carried by this matrix does not support numeric operations
at Microsoft.FSharp.Math.DenseMatrix`1.get_ElementOps()
at Microsoft.FSharp.Math.RawMatrixOps.Unspecialized.inplace_addDMGU[T](DenseMatrix`1 a, DenseMatrix`1 b)"

The line of code that generates this is:

Math.Matrix.Generic.inplace_add m1 m2

The type I store in this generic matrix has already implemented INumeric

I don't understand what I havent done. To be specific the type I am wanting to create is a similar to a fraction where it has two parts (both of type int) however the operators behave differently hence why I am not using Math.BigRational

.

Hi,
you can do this by specifying how the basic numeric operations for your type should behave. This can be done by implementing an interface (INumeric<'a>) and by registering the implementation. The following code shows how to do this for a very basic record type:

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#light

open Microsoft.FSharp.Math

type N = { Numb : float }

// Implement basic operations for our new type
let numN = 
  { new INumeric<N> with
      member x.Abs a = a
      member x.Add({ Numb = a }, { Numb = b }) = { Numb = a + b }
      member x.Multiply({ Numb = a }, { Numb = b }) = { Numb = a * b }
      member x.Negate({ Numb = a }) = { Numb = -a }
      member x.Subtract({ Numb = a }, { Numb = b }) = { Numb = a - b }
      member x.Parse(_, _, _) = failwith "not supported"
      member x.Sign({ Numb = a }) = sign a
      member x.ToString (n, _, _) = (box n).ToString()
      member x.One = { Numb = 1.0 }
      member x.Zero = { Numb = 0.0 }
   }

// Register the association
Math.GlobalAssociations.RegisterNumericAssociation(numN)

let vec = Vector.Generic.of_list [ { Numb = 1.0 }; { Numb = 2.0} ]
printfn "%A" (vec .* vec) // works!
By on 11/10/2008 3:47 AM ()

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