Return (maximum - minimum) along the the given dimension
(i.e. peak-to-peak value).
Parameters:
axis : {None, int}, optional
Axis along which to find the peaks. If None (default) the
flattened array is used.
out : {None, array_like}, optional
Alternative output array in which to place the result. It must
have the same shape and buffer length as the expected output
but the type will be cast if necessary.
fill_value : {var}, optional
Value used to fill in the masked values.
Returns:
ptp : ndarray.
A new array holding the result, unless out was
specified, in which case a reference to out is returned.
