Distance matrix: Can I do the 'Singleton expansion with a custom function' from http://www.mathworks.com/help/matlab/ref/bsxfun.html in breeze? Something like bsxfun in octave?

[Daniel Korzekwa]

Hello,

I need computing distance matrix for a given vector, something which in octave is very quick with  bsxfun(@minus,x',x). 

Does jBlas or other java/scala library provide some functions similar to bsxfun for singleton expansion?

[Mikio Braun]

Hi Daniel,

jblas has overloaded versions to subtract a scalar value from a
vector. There are also functions like addColumnVector, addRowVector
etc. to work with a vector vs. a matrix. Was that the use case you
looked for? What are the dimensions of x' and x?

-M

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Mikio Braun - http://blog.mikiobraun.de, http://twitter.com/mikiobraun

[Daniel Korzekwa]

x - covariance matrix used by stochastic inference for multi output Gaussian process (https://github.com/danielkorzekwa/bayes-scala-gp/blob/master/doc/cogp/cogp.md)

x: [M x D] - M number of training points < 500, D - number of predictor features (a few)

covMatrix: [M x M], is computed many (hundreds) times. The most time consuming operation is computing squared distance matrix.