kelvin_bei_vectorreturns an array of values for the Kelvin function .
For full information please refer to the NAG Library document for s19ap
- xfloat, array-like, shape
The argument of the function, for .
- ffloat, ndarray, shape
, the function values.
- ivalidint, ndarray, shape
contains the error code for , for .
is too large for an accurate result to be returned. contains zero. The threshold value is the same as for = 1 in
- (errno )
On entry, .
- (errno )
On entry, at least one value of was invalid.
Check for more information.
kelvin_bei_vectorevaluates an approximation to the Kelvin function for an array of arguments , for .
Note: , so the approximation need only consider .
The function is based on several Chebyshev expansions:
where , ,
and , , , and are expansions in the variable .
When is sufficiently close to zero, the result is computed as . If this result would underflow, the result returned is .
For large , there is a danger of the result being totally inaccurate, as the error amplification factor grows in an essentially exponential manner;, therefore, the function must fail.
NIST Digital Library of Mathematical Functions