asin() [7/9]

var stan::math::asin ( const var &  x )

inline

Return the principal value of the arc sine, in radians, of the specified variable (cmath).

The derivative is defined by

\(\frac{d}{dx} \arcsin x = \frac{1}{\sqrt{1 - x^2}}\).

\[ \mbox{asin}(x) = \begin{cases} \textrm{NaN} & \mbox{if } x < -1\\ \arcsin(x) & \mbox{if } -1\leq x\leq 1 \\ \textrm{NaN} & \mbox{if } x > 1\\[6pt] \textrm{NaN} & \mbox{if } x = \textrm{NaN} \end{cases} \]

\[ \frac{\partial\, \mbox{asin}(x)}{\partial x} = \begin{cases} \textrm{NaN} & \mbox{if } x < -1\\ \frac{\partial\, \arcsin(x)}{\partial x} & \mbox{if } -1\leq x\leq 1 \\ \textrm{NaN} & \mbox{if } x < -1\\[6pt] \textrm{NaN} & \mbox{if } x = \textrm{NaN} \end{cases} \]

\[ \frac{\partial \, \arcsin(x)}{\partial x} = \frac{1}{\sqrt{1-x^2}} \]

Parameters

x	Variable in range [-1, 1].

Returns

Arc sine of variable, in radians.

Definition at line 53 of file asin.hpp.