MathNet Raise Scalar by a Matrix

Question

I'm attempting to implement Logistic regression in .net using MathNumerics Linear Algebra libraries. I need to implement the following equation and am unsure of how to accomplish raising e by a matrix.

1.0 ./ (1.0 + E .^ (-1 .* Z))

where Z is a matrix and E is the mathematical constant e.

So the problematic section of code is E .^ Z

score 2 · Accepted Answer · answered Jun 02 '16 at 14:08

2

let sigmoid (z : Matrix<double>) : Matrix<double> =
        z.Map (fun x -> 1.0 / (1.0 + exp (0.0 - x)))

answered Jun 02 '16 at 14:08

Guy Coder

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Of interest: [Sigmoid neurons](http://neuralnetworksanddeeplearning.com/chap1.html#sigmoid_neurons) – Guy Coder Jun 02 '16 at 14:15
Accord .NET has this kind of stuff. Also you can reach out to R with the R typeprovider. http://accord-framework.net/ – s952163 Jun 02 '16 at 14:29
@s952163 Can Accord.NET make use of the GPU? – Guy Coder Jun 02 '16 at 14:35
I'm re-implementing some stuff I have in matlab with a goal to use GPUs at some point. – David Crook Jun 02 '16 at 14:38
@Guy: This is the underlayment for my neural network implementations as well, as you hinted in the first comment :) I'm trying to make as generic as possible. Totally agree. I can't stand waiting for hours as a deep net trains... – David Crook Jun 02 '16 at 14:46
@Guy: I was going to take a look at Cudafy after I get it running with MathNumerics. – David Crook Jun 02 '16 at 14:47
@guycoder probably not but I haven't done anything in gpus. – s952163 Jun 02 '16 at 14:57
@GuyCoder I'm assuming you do this as your day job? You seem to be deeper than most i meet. – David Crook Jun 02 '16 at 16:09
actually I'm starting to think this isn't right...need to think a bit first, but I'm getting poor results.. – David Crook Jun 02 '16 at 21:14
sigmoid in a binary classifier should return a scalar, in a multi-class should return a column vector of scalars – David Crook Jun 02 '16 at 21:15
no, I think its right and my head is messed up...I'll post back in a bit. I need to get a coffee or something – David Crook Jun 02 '16 at 21:20

MathNet Raise Scalar by a Matrix

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