ACOSH(3) BSD Programmer's Manual ACOSH(3) NNAAMMEE aaccoosshh - inverse hyperbolic cosine function SSYYNNOOPPSSIISS ##iinncclluuddee <<mmaatthh..hh>> _d_o_u_b_l_e aaccoosshh(_d_o_u_b_l_e _x); DDEESSCCRRIIPPTTIIOONN The aaccoosshh() function computes the inverse hyperbolic cosine of the real argument _x. For a discussion of error due to roundoff, see math(3). RREETTUURRNN VVAALLUUEESS The aaccoosshh() function returns the inverse hyperbolic cosine of _x. On the VAX and Tahoe, if the argument is less than one aaccoosshh() sets the global variable _e_r_r_n_o to EDOM and causes a reserved operand fault. SSEEEE AALLSSOO asinh(3), atanh(3), exp(3), infnan(3) math(3), HHIISSTTOORRYY The aaccoosshh() function appeared in 4.3BSD. 4.3 Berkeley Distribution June 4, 1993 1