# arcsin function

(Shortest import: `from brian2 import arcsin)`

brian2.units.unitsafefunctions.arcsin(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature])

  Inverse sine, element-wise.

  Parameters:

    x : array_like

    > `y`-coordinate on the unit circle.

    out : ndarray, None, or tuple of ndarray and None, optional

    > A location into which the result is stored. If provided, it must have a shape that the inputs broadcast to. If not provided or None, a freshly-allocated array is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.

    where : array_like, optional

    > This condition is broadcast over the input. At locations where the condition is True, the `out` array will be set to the ufunc result. Elsewhere, the `out` array will retain its original value. Note that if an uninitialized `out` array is created via the default `out=None`, locations within it where the condition is False will remain uninitialized.

    **kwargs :

    > For other keyword-only arguments, see the ufunc docs.

  Returns:

    angle : ndarray

    > The inverse sine of each element in `x`, in radians and in the closed interval `[-pi/2, pi/2]`. This is a scalar if `x` is a scalar.

  See also

  `sin()`, `cos()`, `arccos()`, `tan()`, `arctan()`, `arctan2`, `emath.arcsin`

  Notes

  `arcsin()` is a multivalued function: for each `x` there are infinitely many numbers `z` such that \(sin(z) = x\). The convention is to return the angle `z` whose real part lies in [-pi/2, pi/2].

  For real-valued input data types, arcsin always returns real output. For each value that cannot be expressed as a real number or infinity, it yields `nan` and sets the `invalid` floating point error flag.

  For complex-valued input, `arcsin()` is a complex analytic function that has, by convention, the branch cuts [-inf, -1] and [1, inf] and is continuous from above on the former and from below on the latter.

  The inverse sine is also known as `asin` or sin^{-1}.

  References

  Abramowitz, M. and Stegun, I. A., Handbook of Mathematical Functions, 10th printing, New York: Dover, 1964, pp. 79ff. https://personal.math.ubc.ca/~cbm/aands/page_79.htm

  Examples

      >>> import numpy as np
      >>> np.arcsin(1)     # pi/2
      1.5707963267948966
      >>> np.arcsin(-1)    # -pi/2
      -1.5707963267948966
      >>> np.arcsin(0)
      0.0