# Gudermannian

Gudermannian[z]

gives the Gudermannian function .

# Details • Mathematical function, suitable for both symbolic and numerical manipulation.
• The Gudermannian function is generically defined by .
• Gudermannian[z] has branch cut discontinuities in the complex plane running from to for integers , where the function is continuous from the right.
• Gudermannian can be evaluated to arbitrary numerical precision.
• Gudermannian automatically threads over lists.
• Gudermannian can be used with Interval and CenteredInterval objects. »

# Examples

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## Basic Examples(4)

Evaluate numerically:

Plot over a subset of the reals:

Plot over a subset of the complexes:

Series expansion at the origin:

## Scope(38)

### Numerical Evaluation(6)

Evaluate numerically:

Evaluate to high precision:

The precision of the output tracks the precision of the input:

Complex number input:

Evaluate efficiently at high precision:

Exp threads elementwise over lists and matrices:

Gudermannian can be used with Interval and CenteredInterval objects:

### Specific Values(3)

The value at zero:

Values at infinity:

Find a value of for which the using Solve:

Substitute in the result:

Visualize the result:

### Visualization(3)

Plot the Gudermannian function:

Plot the real part of Gudermannian[x+ I y]:

Plot the imaginary part of Gudermannian[x+ I y]:

Polar plot with :

### Function Properties(11)

Gudermannian is defined for all real values:

Gudermannian is defined for all complex values except branch points:

Real range: Gudermannian has the mirror property :

Gudermannian is an odd function: is an analytic function of for real :

It is neither analytic nor meromorphic in the complex plane:

Gudermannian is non-decreasing:

Gudermannian is injective:

Not surjective:

Gudermannian is neither non-negative nor non-positive:

Gudermannian has no singularities or discontinuities:

Gudermannian is neither convex nor concave:

### Differentiation(3)

The first derivative with respect to z:

Higher derivatives with respect to z:

Plot the higher derivatives with respect to z:

Formula for the derivative with respect to z:

### Integration(4)

Compute the indefinite integral using Integrate:

Verify the anti-derivative:

Definite integral:

The definite integral of Gudermannian over a period is 0:

More integrals:

### Series Expansions(4)

Find the Taylor expansion using Series:

Plots of the first three approximations around :

The first-order Fourier series:

The Taylor expansion at a generic point:

Gudermannian can be applied to a power series:

### Function Representations(4)

Gudermannian can be represented in terms of Exp and ArcTan on the real line:

Representation as an integral on the real line:

Since Gudermannian is odd, the same result is obtained for negative :

Gudermannian can be represented in terms of Tanh and ArcTan away from the imaginary axis:

This representation is invalid on the half that is further from the origin of each branch cut strip:

Represent Gudermannian using Piecewise:

This representation is correct at all points, including branch cuts:

## Applications(3)

Nonperiodic solution of a pendulum equation:

Solve a differential equation with the Gudermannian function as the inhomogeneous term:

The cumulative distribution function (CDF) of the standard distribution of the hyperbolic secant is a scaled and shifted version of the Gudermannian function:

## Properties & Relations(2)

Use FunctionExpand to expand Gudermannian in terms of elementary functions:

Use FullSimplify to prove identities involving the Gudermannian function: