ⅆ⁡c′ⅆ⁡ν=2⁢c′c′2-ν2⁢∫0∞(c′2⁢cosh⁡(2⁢t)-ν2)⁢K0⁡(2⁢c′⁢sinh⁡t)⁢ⅇ-2⁢ν⁢t⁢ⅆ⁡t,