In this question: In F# how can I produce an expression with a type of Func<obj>? it is shown that a single valued lambda expression is automatically cast/converted to a Func type and then accepted in the function.
I'm working with the MathNet.Numerics library and can confirm this by integrating x^2 between 0 and 10:
#r "../packages/MathNet.Numerics.3.20.0/lib/net40/MathNet.Numerics.dll"
#r "../packages/MathNet.Numerics.FSharp.3.20.0/lib/net40/MathNet.Numerics.FSharp.dll"
#load "Library1.fs"
open Library3
// Define your library scripting code here
open MathNet.Numerics.Integration
let integral = DoubleExponentialTransformation.Integrate((fun x -> x**2.0), 0.0, 10.0, 1.0)
val answer : float = 333.3333333
However, I can't get this to work with multiple valued functions. When I try this I get a type error. Does anyone know a work around for this?
open MathNet.Numerics.Optimization
open MathNet.Numerics.LinearAlgebra.Double
let newAnswer = BfgsSolver.Solve(DenseVector[|1.0, 1.0|],
(fun x y -> (x + y - 5.0) ** 2.0 + (y - x*x - 4.0) ** 2.0),
(fun x y -> DenseVector[| 2.0 * (x + y - 5.0) - 4.0 * x * (y - x*x - 4);
2.0 * (x + y - 5.0) + 2.0 * (y - x*x - 4.0) |])
)
and I get the following error...
Script.fsx(20,34): error FS0193: Type constraint mismatch. The type
''a -> 'b -> 'c'
is not compatible with type
'System.Func<MathNet.Numerics.LinearAlgebra.Vector<float>,float>'