Golang : Create matrix with Gonum Matrix package example

Here is an example of how to create and display matrix properly in Golang with Gonum package. Nothing special in this tutorial, will write another tutorial on how to find the matrix determinants and performing matrix calculations later on.

Here you go!

 package main

 import (
 "fmt"
 "github.com/gonum/matrix/mat64"
 )

 func main() {
 m := mat64.NewDense(3, 5, nil)

 // fill in m with some elements
 for i := 0; i < 3; i++ {
 m.Set(i, i, 99)
 }

 // wrong way to print matrix
 fmt.Println("m : ", m)

 // proper way
 // refer to https://godoc.org/github.com/gonum/matrix/mat64#Excerpt
 fmt.Printf("m :\n%v\n\n", mat64.Formatted(m, mat64.Prefix(" "), mat64.Excerpt(2)))

 // print all m elements
 fmt.Printf("m :\n%v\n\n", mat64.Formatted(m, mat64.Prefix(""), mat64.Excerpt(0)))

 data := []float64{1, 2, 3}
 m2 := mat64.NewDense(3, 1, data)

 // print all m2 elements
 fmt.Printf("m2 :\n%v\n\n", mat64.Formatted(m2, mat64.Prefix(""), mat64.Excerpt(0)))

 // to build this matrix
 // ⎡1  2  3⎤
 // ⎢4  5  6⎥
 // ⎣7  8  9⎦

 // use SetRow or SetCol
 m3 := mat64.NewDense(3, 3, nil)
 m3.SetRow(0, data)

 data2 := []float64{4, 5, 6}
 m3.SetRow(1, data2)

 data3 := []float64{7, 8, 9}
 m3.SetRow(2, data3)

 // print all m3 elements
 fmt.Printf("m3 :\n%v\n\n", mat64.Formatted(m3, mat64.Prefix(""), mat64.Excerpt(0)))

 // get transpose with m3.T()
 fmt.Printf("m3 transpose :\n%v\n\n", mat64.Formatted(m3.T(), mat64.Prefix(""), mat64.Excerpt(0)))

 }

Output:

m : &{{3 5 5 [99 0 0 0 0 0 99 0 0 0 0 0 99 0 0]} 3 5}

m :

Dims(3, 5)

⎡99 0 ... ... 0 0⎤

⎢ 0 99 0 0⎥

⎣ 0 0 ... ... 0 0⎦

---

m :

⎡99 0 0 0 0⎤

⎢ 0 99 0 0 0⎥

⎣ 0 0 99 0 0⎦

---

m2 :

⎡1⎤

⎢2⎥

⎣3⎦

---

m3 :

⎡1 2 3⎤

⎢4 5 6⎥

⎣7 8 9⎦

---

m3 transpose :

⎡1 4 7⎤

⎢2 5 8⎥

⎣3 6 9⎦

References:

https://godoc.org/github.com/gonum/matrix/mat64#Dense.SetRow

https://github.com/gonum/matrix