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Matrix and RowVector additions
f#

Hi All,

I have been puzzling this but i just cannot get it to work for me.
Maybe you can help and push me in the right direction.

Suppose I have the following matrix and rowvector:

let m = matrix [[1.0; 2.0; 3.0];
[4.0; 5.0; 6.0];
[7.0; 8.0; 9.0]]

let r = rowvec [|10.0; 11.0; 12.0|];;

How would I add r.Item i to each member of m.Column i
so that the result will be the following:

let result = matrix [[11.0; 13.0; 15.0];
[14.0; 16.0; 18.0];
[17.0; 19.0; 21.0]];;

I have been thinking about a for loop, but there
must be a more 'functional' way of doing this.
I cannot get foldByCol to work for me, anyone has any idea?

TIA.

Regards,

Koen

.

Here's a not very elegant solution:

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let m = matrix [[1.0; 2.0; 3.0];
                [4.0; 5.0; 6.0];
                [7.0; 8.0; 9.0]]


let r = [|10.0; 11.0; 12.0|]


let result = Array.init m.NumRows (fun _ -> r) |> Matrix.ofSeq |> (+) m

Mau

By on 5/28/2010 2:19 AM ()

I don't think it's worse than my solution

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let m = matrix [[1.0; 2.0; 3.0];
                [4.0; 5.0; 6.0];
               

 [7.0; 8.0; 9.0]];;


let r = [|10.0; 11.0; 12.0|];;

let result = matrix [for i in 0..m.NumRows-1 do
               yield
                    [for j in 0..m.NumCols-1 do
                        yield m.[i,j] + r.[j]]];;

Koen

By on 5/28/2010 8:24 AM ()

Was trying to find a method signature that returned a matrix seems like map and mapi are the only ones. When there starts being lots of functions it would be amazing to be able to search for function using a signature, is this already possible ? 

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<code lang=fsharp>open Microsoft.FSharp.Math

let m = matrix [[1.0; 2.0; 3.0];


[4.0; 5.0; 6.0];


[7.0; 8.0; 9.0]]

//changed it to a vector


let r = vector [|10.0; 11.0; 12.0|];;


let result = matrix [[11.0; 13.0; 15.0];


[14.0; 16.0; 18.0];


[17.0; 19.0; 21.0]];;


//maybe something a little more functional


m |> Matrix.mapi( fun i j elemFromM ->  elemFromM + r.[j])

//using matrix basics


let temp = Matrix.init 3 3 ( fun i j -> 1.0 )


temp*Matrix.initDiagonal(r) + m

//i guess this is also doing a for loop


let temp2 = Matrix.init 3 3 (fun i j -> r.Item(j) + m.Item(i,j) )
By on 5/31/2010 3:04 AM ()

When there starts being lots of functions it would be amazing to be able to search for function using a signature, is this already possible ?

Reminds me of this question: [link:stackoverflow.com]

By on 5/31/2010 6:16 AM ()

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