numpy.sqrt¶

numpy.
sqrt
(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True[, signature, extobj]) = <ufunc 'sqrt'>¶ Return the nonnegative squareroot of an array, elementwise.
Parameters:  x : array_like
The values whose squareroots are required.
 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 freshlyallocated array is returned. A tuple (possible only as a keyword argument) must have length equal to the number of outputs.
 where : array_like, optional
Values of True indicate to calculate the ufunc at that position, values of False indicate to leave the value in the output alone.
 **kwargs
For other keywordonly arguments, see the ufunc docs.
Returns:  y : ndarray
An array of the same shape as x, containing the positive squareroot of each element in x. If any element in x is complex, a complex array is returned (and the squareroots of negative reals are calculated). If all of the elements in x are real, so is y, with negative elements returning
nan
. If out was provided, y is a reference to it. This is a scalar if x is a scalar.
参见
lib.scimath.sqrt
 A version which returns complex numbers when given negative reals.
Notes
sqrt has–consistent with common convention–as its branch cut the real “interval” [inf, 0), and is continuous from above on it. A branch cut is a curve in the complex plane across which a given complex function fails to be continuous.
Examples
>>> np.sqrt([1,4,9]) array([ 1., 2., 3.])
>>> np.sqrt([4, 1, 3+4J]) array([ 2.+0.j, 0.+1.j, 1.+2.j])
>>> np.sqrt([4, 1, numpy.inf]) array([ 2., NaN, Inf])