github.com/jingcheng-WU/gonum@v0.9.1-0.20210323123734-f1a2a11a8f7b/num/dual/dual_example_test.go (about)

     1  // Copyright ©2018 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package dual_test
     6  
     7  import (
     8  	"fmt"
     9  
    10  	"github.com/jingcheng-WU/gonum/num/dual"
    11  )
    12  
    13  func ExampleNumber_fike() {
    14  	// Calculate the value and derivative of the function
    15  	// e^x/(sqrt(sin(x)^3 + cos(x)^3)).
    16  	fn := func(x dual.Number) dual.Number {
    17  		return dual.Mul(
    18  			dual.Exp(x),
    19  			dual.Inv(dual.Sqrt(
    20  				dual.Add(
    21  					dual.PowReal(dual.Sin(x), 3),
    22  					dual.PowReal(dual.Cos(x), 3)))))
    23  	}
    24  
    25  	v := fn(dual.Number{Real: 1.5, Emag: 1})
    26  	fmt.Printf("v=%.4f\n", v)
    27  	fmt.Printf("fn(1.5)=%.4f\nfn'(1.5)=%.4f\n", v.Real, v.Emag)
    28  
    29  	// Output:
    30  	//
    31  	// v=(4.4978+4.0534ϵ)
    32  	// fn(1.5)=4.4978
    33  	// fn'(1.5)=4.0534
    34  }