Chi Chi_sub Ci Ci_sub Shi Shi_sub Si Si_sub

Chi_sub() Sub Chi_sub ( Ret As  Double, X As  Double, Optional Info As  Long  ) Hyperbolic cosine integral Chi(x) (Subroutine version) Purpose Computes the hyperbolic cosine integral. Chi(x) = ∫ (cosh(t)-1)/t dt [0, x] + ln(x) + γ (γ: Euler's constant) Parameters [out] Ret Hyperbolic cosine integral Chi(x). [in] X Argument x. (x != 0) (If x < 0, returns the real part = Chi(|x|)) [out] Info (Optional) = 0: Successful exit. = -1: The argument X had an illegal value. (X = 0) = 1: Floating point range error.