How do I element-wise square root a gonum matrix?

Question

I was going to use Pow but it only seems to accept powering by integer values.

For example, the element-wise square root matrix m of matrix a.:

a = ⎡ 4   9⎤
    ⎣16  25⎦

m = ⎡2  3⎤
    ⎣4  5⎦

Answer 1

For an element-wise square root of a matrix, write something like this:

package main

import (
    "fmt"
    "math"

    "gonum.org/v1/gonum/mat"
)

func main() {
    a := mat.NewDense(2, 2, []float64{
        4, 9,
        16, 25,
    })
    fa := mat.Formatted(a, mat.Prefix("    "), mat.Squeeze())
    fmt.Printf("a = %v\n\n", fa)

    m := new(mat.Dense)
    m.Apply(func(i, j int, v float64) float64 { return math.Sqrt(v) }, a)
    fm := mat.Formatted(m, mat.Prefix("    "), mat.Squeeze())
    fmt.Printf("m = %v\n\n", fm)
}

Output:

a = ⎡ 4   9⎤
    ⎣16  25⎦

m = ⎡2  3⎤
    ⎣4  5⎦