Inverse sine elementwise.
Parameters:  x : array_like
out : ndarray, optional


Returns:  angle : ndarray

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 realvalued 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 complexvalued input, arcsin is a complex analytical function that has 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
[R6]  M. Abramowitz and I.A. Stegun, “Handbook of Mathematical Functions”, 10th printing, 1964, pp. 79. http://www.math.sfu.ca/~cbm/aands/ 
[R7]  Wikipedia, “Inverse trigonometric function”, http://en.wikipedia.org/wiki/Inverse_trigonometric_function 
Examples
>>> np.arcsin(1) # pi/2
1.5707963267948966
>>> np.arcsin(1) # pi/2
1.5707963267948966
>>> np.arcsin(0)
0.0