;+ ; NAME: ; SECH ; ; PURPOSE: ; Calculates the hyperbolic inverse cosine function (sech). ; ; CATEGORY: ; Math ; ; CALLING SEQUENCE: ; Result = SECH(X) ; ; INPUTS: ; X: Argument to sech (may be an array). ; ; OUTPUTS: ; 1 / cosh(X) ; ; EXAMPLE: ; IDL> PRINT, SECH(1.) ; 0.648054 ; ; MODIFICATION HISTORY: ; Written by: Jeremy Bailin ; 12 June 2008 Public release in JBIU ;- function sech, x return, 1.0/cosh(x) end