2015 008 Additional math functions

Proposal 2015-008

Additional math functions

Author: Andreas Rossberg
Last revised: August 22, 2015
Status: proposed
Discussion: issue #9

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Synopsis

signature MATH

This proposal adds the inverse hyperbolic functions to the MATH signature.

Interface

val asinh : real -> real
val acosh : real -> real
val atanh : real -> real

Description

• asinh x
  returns the arc hyperbolic sine of x, expressed in radians. It is the inverse of the sinh function.

• acosh x
  returns the nonnegative arc hyperbolic cosine of x, expressed in radians. It is the inverse of the cosh function. If x < 1.0, then the Domain exception is raised.

• atanh x
  returns the arc hyperbolic tangent of x, expressed in radians. It is the inverse of the tanh function. The Domain exception is raised if x <= ~1.0 or 1.0 <= x.

Rationale

These functions are fairly standard in contemporary languages' math libraries.

Impact

The addition of these functions should not affect existing programs.

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History

• [2015-08-22] Added more detailed description of functions and made some formatting changes for consistency. [JHR].

• [2015-08-16] Proposed

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