gives the hyperbolic cotangent of z.
- Mathematical function, suitable for both symbolic and numerical manipulation.
- Cosh[z]/Sinh[z] is automatically converted to Coth[z]. TrigFactorList[expr] does decomposition.
- For certain special arguments, Coth automatically evaluates to exact values.
- Coth can be evaluated to arbitrary numerical precision.
- Coth automatically threads over lists.
Background & Context
- Coth is the hyperbolic cotangent function, which is the hyperbolic analogue of the Cot circular function used throughout trigonometry. Coth[α] is defined as the ratio of the corresponding hyperbolic cosine and hyperbolic sine functions via . Coth may also be defined as , where is the base of the natural logarithm Log.
- Coth automatically evaluates to exact values when its argument is the (natural) logarithm of a rational number. When given exact numeric expressions as arguments, Coth may be evaluated to arbitrary numeric precision. TrigFactorList can be used to factor expressions involving Coth into terms containing Sinh, Cosh, Sin, and Cos. Other operations useful for manipulation of symbolic expressions involving Coth include TrigToExp, TrigExpand, Simplify, and FullSimplify.
- Coth threads element-wise over lists and matrices. In contrast, MatrixFunction can be used to give the hyperbolic cotangent of a square matrix (i.e. the power series for the hyperbolic cotangent function with ordinary powers replaced by matrix powers) as opposed to the hyperbolic cotangents of the individual matrix elements.
- Coth[x] approaches for small negative x and for large positive x. Coth satisfies an identity similar to the Pythagorean identity satisfied by Cot, namely . The definition of the hyperbolic cotangent function is extended to complex arguments by way of the identities and . Coth has poles at values for an integer and evaluates to ComplexInfinity at these points. Coth[z] has series expansion about the origin that may be expressed in terms of the Bernoulli numbers BernoulliB.
- The inverse function of Coth is ArcCoth. Other related mathematical functions include Tanh, Cot, and Cosh.
Examplesopen allclose all
Basic Examples (5)
Numerical Evaluation (6)
Specific Values (5)
Plot the Coth function:
Function Properties (12)
Coth is defined for all real values except 0:
Coth achieves all real values except from the open interval :
Coth is an odd function:
Coth has the mirror property :
Coth is not an analytic function:
Coth is neither non-decreasing nor non-increasing:
Coth is injective:
Coth is not surjective:
Coth is neither non-negative nor non-positive:
Coth is neither convex nor concave:
Indefinite integral of Coth:
Series Expansions (3)
Function Identities and Simplifications (6)
Function Representations (4)
Representation through Cot:
Plot the absolute value over the complex plane:
Closed form for Newton iterations for square roots of integers:
Compare with explicit iterations:
Sum over bosonic Matsubara frequencies by integrating over a product with Coth:
Temperature‐dependent Brillouin function for dipoles in a magnetic field:
Low‐ and high‐temperature behavior:
Solve a differential equation with the Coth function as inhomogeneous part:
Properties & Relations (11)
Basic parity and periodicity properties of Coth get automatically applied:
Use FunctionExpand to express special values in radicals:
Compose with inverse functions:
Solve a hyperbolic equation:
Numerically find a root of a transcendental equation:
Reduce a hyperbolic equation:
Obtain Coth from sums and integrals:
Coth appears in special cases of special functions:
Coth is a numeric function:
Possible Issues (4)
Machine-precision input is insufficient to give a correct answer:
With exact input, the answer is correct:
A larger setting for $MaxExtraPrecision can be needed:
No power series exists at infinity, where Coth has an essential singularity:
In TraditionalForm, parentheses are needed around the argument:
Neat Examples (1)
Plot Coth at infinity:
Wolfram Research (1988), Coth, Wolfram Language function, https://reference.wolfram.com/language/ref/Coth.html (updated 1996).
Wolfram Language. 1988. "Coth." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 1996. https://reference.wolfram.com/language/ref/Coth.html.
Wolfram Language. (1988). Coth. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Coth.html