U⁡(a,b,z)=2⁢z12-12⁢bΓ⁡(a)⁢Γ⁡(a-b+1)⁢∫0∞ⅇ-t⁢ta-12⁢b-12⁢Kb-1⁡(2⁢z⁢t)⁢ⅆ⁡t,