+++ /dev/null
-// Copyright ©2017 The Gonum Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package mat_test
-
-import (
- "fmt"
-
- "gonum.org/v1/gonum/mat"
-)
-
-func ExampleDense_Add() {
- // Initialize two matrices, a and b.
- a := mat.NewDense(2, 2, []float64{
- 1, 0,
- 1, 0,
- })
- b := mat.NewDense(2, 2, []float64{
- 0, 1,
- 0, 1,
- })
-
- // Add a and b, placing the result into c.
- // Notice that the size is automatically adjusted
- // when the receiver has zero size.
- var c mat.Dense
- c.Add(a, b)
-
- // Print the result using the formatter.
- fc := mat.Formatted(&c, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("c = %v", fc)
-
- // Output:
- //
- // c = ⎡1 1⎤
- // ⎣1 1⎦
-}
-
-func ExampleDense_Sub() {
- // Initialize two matrices, a and b.
- a := mat.NewDense(2, 2, []float64{
- 1, 1,
- 1, 1,
- })
- b := mat.NewDense(2, 2, []float64{
- 1, 0,
- 0, 1,
- })
-
- // Subtract b from a, placing the result into a.
- a.Sub(a, b)
-
- // Print the result using the formatter.
- fa := mat.Formatted(a, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("a = %v", fa)
-
- // Output:
- //
- // a = ⎡0 1⎤
- // ⎣1 0⎦
-}
-
-func ExampleDense_MulElem() {
- // Initialize two matrices, a and b.
- a := mat.NewDense(2, 2, []float64{
- 1, 2,
- 3, 4,
- })
- b := mat.NewDense(2, 2, []float64{
- 1, 2,
- 3, 4,
- })
-
- // Multiply the elements of a and b, placing the result into a.
- a.MulElem(a, b)
-
- // Print the result using the formatter.
- fa := mat.Formatted(a, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("a = %v", fa)
-
- // Output:
- //
- // a = ⎡1 4⎤
- // ⎣9 16⎦
-}
-
-func ExampleDense_DivElem() {
- // Initialize two matrices, a and b.
- a := mat.NewDense(2, 2, []float64{
- 5, 10,
- 15, 20,
- })
- b := mat.NewDense(2, 2, []float64{
- 5, 5,
- 5, 5,
- })
-
- // Divide the elements of a by b, placing the result into a.
- a.DivElem(a, b)
-
- // Print the result using the formatter.
- fa := mat.Formatted(a, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("a = %v", fa)
-
- // Output:
- //
- // a = ⎡1 2⎤
- // ⎣3 4⎦
-}
-
-func ExampleDense_Inverse() {
- // Initialize two matrices, a and ia.
- a := mat.NewDense(2, 2, []float64{
- 4, 0,
- 0, 4,
- })
- var ia mat.Dense
-
- // Take the inverse of a and place the result in ia.
- ia.Inverse(a)
-
- // Print the result using the formatter.
- fa := mat.Formatted(&ia, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("ia = %.2g\n\n", fa)
-
- // Confirm that A * A^-1 = I
- var r mat.Dense
- r.Mul(a, &ia)
- fr := mat.Formatted(&r, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("r = %v\n\n", fr)
-
- // The Inverse operation, however, is numerically unstable,
- // and should typically be avoided.
- // For example, a common need is to find x = A^-1 * b.
- // In this case, the SolveVec method of VecDense
- // (if b is a Vector) or Solve method of Dense (if b is a
- // matrix) should used instead of computing the Inverse of A.
- b := mat.NewDense(2, 2, []float64{
- 2, 0,
- 0, 2,
- })
- var x mat.Dense
- x.Solve(a, b)
-
- // Print the result using the formatter.
- fx := mat.Formatted(&x, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("x = %v", fx)
-
- // Output:
- //
- // ia = ⎡0.25 -0⎤
- // ⎣ 0 0.25⎦
- //
- // r = ⎡1 0⎤
- // ⎣0 1⎦
- //
- // x = ⎡0.5 0⎤
- // ⎣ 0 0.5⎦
-}
-
-func ExampleDense_Mul() {
- // Initialize two matrices, a and b.
- a := mat.NewDense(2, 2, []float64{
- 4, 0,
- 0, 4,
- })
- b := mat.NewDense(2, 3, []float64{
- 4, 0, 0,
- 0, 0, 4,
- })
-
- // Take the matrix product of a and b and place the result in c.
- var c mat.Dense
- c.Mul(a, b)
-
- // Print the result using the formatter.
- fc := mat.Formatted(&c, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("c = %v", fc)
-
- // Output:
- //
- // c = ⎡16 0 0⎤
- // ⎣ 0 0 16⎦
-}
-
-func ExampleDense_Exp() {
- // Initialize a matrix a with some data.
- a := mat.NewDense(2, 2, []float64{
- 1, 0,
- 0, 1,
- })
-
- // Take the exponential of the matrix and place the result in m.
- var m mat.Dense
- m.Exp(a)
-
- // Print the result using the formatter.
- fm := mat.Formatted(&m, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("m = %4.2f", fm)
-
- // Output:
- //
- // m = ⎡2.72 0.00⎤
- // ⎣0.00 2.72⎦
-}
-
-func ExampleDense_Pow() {
- // Initialize a matrix with some data.
- a := mat.NewDense(2, 2, []float64{
- 4, 4,
- 4, 4,
- })
-
- // Take the second power of matrix a and place the result in m.
- var m mat.Dense
- m.Pow(a, 2)
-
- // Print the result using the formatter.
- fm := mat.Formatted(&m, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("m = %v\n\n", fm)
-
- // Take the zeroth power of matrix a and place the result in n.
- // We expect an identity matrix of the same size as matrix a.
- var n mat.Dense
- n.Pow(a, 0)
-
- // Print the result using the formatter.
- fn := mat.Formatted(&n, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("n = %v", fn)
-
- // Output:
- //
- // m = ⎡32 32⎤
- // ⎣32 32⎦
- //
- // n = ⎡1 0⎤
- // ⎣0 1⎦
-}
-
-func ExampleDense_Scale() {
- // Initialize a matrix with some data.
- a := mat.NewDense(2, 2, []float64{
- 4, 4,
- 4, 4,
- })
-
- // Scale the matrix by a factor of 0.25 and place the result in m.
- var m mat.Dense
- m.Scale(0.25, a)
-
- // Print the result using the formatter.
- fm := mat.Formatted(&m, mat.Prefix(" "), mat.Squeeze())
- fmt.Printf("m = %4.3f", fm)
-
- // Output:
- //
- // m = ⎡1.000 1.000⎤
- // ⎣1.000 1.000⎦
-}
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