gonum: gonum.org/v1/gonum/num/dual

## package dual

`import "gonum.org/v1/gonum/num/dual"`

Package dual provides the dual numeric type and functions. Dual numbers are an extension of the real numbers in the form a+bϵ where ϵ^2=0, but ϵ≠0.

See https://en.wikipedia.org/wiki/Dual_number for details of their properties and uses.

### type Number¶Uses

```type Number struct {
Real, Emag float64
}```

Number is a float64 precision dual number.

#### func Abs¶Uses

`func Abs(d Number) Number`

Abs returns the absolute value of d.

#### func Acos¶Uses

`func Acos(d Number) Number`

Acos returns the inverse cosine of d.

Special cases are:

```Acos(-1) = (Pi-Infϵ)
Acos(1) = (0-Infϵ)
Acos(x) = NaN if x < -1 or x > 1
```

#### func Acosh¶Uses

`func Acosh(d Number) Number`

Acosh returns the inverse hyperbolic cosine of d.

Special cases are:

```Acosh(+Inf) = +Inf
Acosh(1) = (0+Infϵ)
Acosh(x) = NaN if x < 1
Acosh(NaN) = NaN
```

`func Add(x, y Number) Number`

Add returns the sum of x and y.

#### func Asin¶Uses

`func Asin(d Number) Number`

Asin returns the inverse sine of d.

Special cases are:

```Asin(±0) = (±0+Nϵ)
Asin(±1) = (±Inf+Infϵ)
Asin(x) = NaN if x < -1 or x > 1
```

#### func Asinh¶Uses

`func Asinh(d Number) Number`

Asinh returns the inverse hyperbolic sine of d.

Special cases are:

```Asinh(±0) = (±0+Nϵ)
Asinh(±Inf) = ±Inf
Asinh(NaN) = NaN
```

#### func Atan¶Uses

`func Atan(d Number) Number`

Atan returns the inverse tangent of d.

Special cases are:

```Atan(±0) = (±0+Nϵ)
Atan(±Inf) = (±Pi/2+0ϵ)
```

#### func Atanh¶Uses

`func Atanh(d Number) Number`

Atanh returns the inverse hyperbolic tangent of d.

Special cases are:

```Atanh(1) = +Inf
Atanh(±0) = (±0+Nϵ)
Atanh(-1) = -Inf
Atanh(x) = NaN if x < -1 or x > 1
Atanh(NaN) = NaN
```

#### func Cos¶Uses

`func Cos(d Number) Number`

Cos returns the cosine of d.

Special cases are:

```Cos(±Inf) = NaN
Cos(NaN) = NaN
```

#### func Cosh¶Uses

`func Cosh(d Number) Number`

Cosh returns the hyperbolic cosine of d.

Special cases are:

```Cosh(±0) = 1
Cosh(±Inf) = +Inf
Cosh(NaN) = NaN
```

#### func Exp¶Uses

`func Exp(d Number) Number`

Exp returns e**q, the base-e exponential of d.

Special cases are:

```Exp(+Inf) = +Inf
Exp(NaN) = NaN
```

Very large values overflow to 0 or +Inf. Very small values underflow to 1.

#### func Inv¶Uses

`func Inv(d Number) Number`

Inv returns the dual inverse of d.

Special cases are:

```Inv(±Inf) = ±0-0ϵ
Inv(±0) = ±Inf-Infϵ
```

#### func Log¶Uses

`func Log(d Number) Number`

Log returns the natural logarithm of d.

Special cases are:

```Log(+Inf) = (+Inf+0ϵ)
Log(0) = (-Inf±Infϵ)
Log(x < 0) = NaN
Log(NaN) = NaN
```

#### func Mul¶Uses

`func Mul(x, y Number) Number`

Mul returns the dual product of x and y.

#### func Pow¶Uses

`func Pow(d, p Number) Number`

Pow returns d**r, the base-d exponential of r.

#### func PowReal¶Uses

`func PowReal(d Number, p float64) Number`

PowReal returns x**p, the base-x exponential of p.

Special cases are (in order):

```PowReal(NaN+xϵ, ±0) = 1+NaNϵ for any x
PowReal(x, ±0) = 1 for any x
PowReal(1+xϵ, y) = 1+xyϵ for any y
PowReal(x, 1) = x for any x
PowReal(NaN+xϵ, y) = NaN+NaNϵ
PowReal(x, NaN) = NaN+NaNϵ
PowReal(±0, y) = ±Inf for y an odd integer < 0
PowReal(±0, -Inf) = +Inf
PowReal(±0, +Inf) = +0
PowReal(±0, y) = +Inf for finite y < 0 and not an odd integer
PowReal(±0, y) = ±0 for y an odd integer > 0
PowReal(±0, y) = +0 for finite y > 0 and not an odd integer
PowReal(-1, ±Inf) = 1
PowReal(x+0ϵ, +Inf) = +Inf+NaNϵ for |x| > 1
PowReal(x+yϵ, +Inf) = +Inf for |x| > 1
PowReal(x, -Inf) = +0+NaNϵ for |x| > 1
PowReal(x, +Inf) = +0+NaNϵ for |x| < 1
PowReal(x+0ϵ, -Inf) = +Inf+NaNϵ for |x| < 1
PowReal(x, -Inf) = +Inf-Infϵ for |x| < 1
PowReal(+Inf, y) = +Inf for y > 0
PowReal(+Inf, y) = +0 for y < 0
PowReal(-Inf, y) = Pow(-0, -y)
PowReal(x, y) = NaN+NaNϵ for finite x < 0 and finite non-integer y
```

#### func Scale¶Uses

`func Scale(f float64, d Number) Number`

Scale returns d scaled by f.

#### func Sin¶Uses

`func Sin(d Number) Number`

Sin returns the sine of d.

Special cases are:

```Sin(±0) = (±0+Nϵ)
Sin(±Inf) = NaN
Sin(NaN) = NaN
```

#### func Sinh¶Uses

`func Sinh(d Number) Number`

Sinh returns the hyperbolic sine of d.

Special cases are:

```Sinh(±0) = (±0+Nϵ)
Sinh(±Inf) = ±Inf
Sinh(NaN) = NaN
```

#### func Sqrt¶Uses

`func Sqrt(d Number) Number`

Sqrt returns the square root of d.

Special cases are:

```Sqrt(+Inf) = +Inf
Sqrt(±0) = (±0+Infϵ)
Sqrt(x < 0) = NaN
Sqrt(NaN) = NaN
```

#### func Sub¶Uses

`func Sub(x, y Number) Number`

Sub returns the difference of x and y, x-y.

#### func Tan¶Uses

`func Tan(d Number) Number`

Tan returns the tangent of d.

Special cases are:

```Tan(±0) = (±0+Nϵ)
Tan(±Inf) = NaN
Tan(NaN) = NaN
```

#### func Tanh¶Uses

`func Tanh(d Number) Number`

Tanh returns the hyperbolic tangent of d.

Special cases are:

```Tanh(±0) = (±0+Nϵ)
Tanh(±Inf) = (±1+0ϵ)
Tanh(NaN) = NaN
```

#### func (Number) Format¶Uses

`func (d Number) Format(fs fmt.State, c rune)`

Format implements fmt.Formatter.

Package dual imports 3 packages (graph) and is imported by 2 packages. Updated 2019-03-01. Refresh now. Tools for package owners.