Have been playing around with Multik this weekend ...

# mathematics

[Peter]

Have been playing around with Multik this weekend and have to say nice performance out of the box (I’m using the JVM version only). One thing I couldn’t figure out how to efficiently copy/set data. What I want to do in a matrix (D2Array<Float>) is to move the last x rows to the first x rows.

I use a “hack”, but I feel this is not very elegantly:

data = data[rows-x until rows].cat(mk.zeros(rows-x, columns))

Does anyone knows a better way of doing this (performance is key) ?

[altavir]

You can check the KMath wrapper: https://github.com/SciProgCentre/kmath/blob/6d47c0ccecd4068cc4c6289741d5dc89931c4a[…]nMain/kotlin/space/kscience/kmath/multik/MultikTensorAlgebra.kt

It does mutations as well as other operations

[roman.belov]

сс @Pavel Gorgulov

[Pavel Gorgulov]

In multik, you can only use set with a smaller dimension and with normal indexing. So for example for a matrix we can do: data[x] = other[y]
For your case:

for (i in 0 until x) {
    if (x + 1 < rows) data[i] = data[x + i]
}

[Peter]

Are there any future plans to have something equivalent to the get API (data[0..100] = data[500..600] )?

[Pavel Gorgulov]

Yes, in next release I plan to rework all the internal get/set logic and add missing methods. Unfortunately, next release will not be as soon as I would like(