2015 008 Additional math functions

Proposal 2015-008

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

signature MATH

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

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

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.

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

The addition of these functions should not affect existing programs.

[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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