atan
(PHP 3, PHP 4 )
atan -- Arc tangent
Description
float atan ( float arg)
Returns the arc tangent of arg in radians. atan() is the
complementary function of tan(), which means that a==tan(atan(a))
for every value of a that is within atan()'s range.
See also: atanh(), asin(), and acos().
atanh
(PHP 4 >= 4.1.0)
atanh -- Inverse hyperbolic tangent
Description
float atanh ( float arg)
Returns the inverse hyperbolic tangent of arg, i.e. the
value whose hyperbolic tangent is arg.
Note: This function is not implemented on Windows platforms.
See also: atan(), asinh(), and acosh().
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