phi ( x -- value )


Vocabulary
picomath

Inputs and outputs
xan object
valuean object


Definition


:: phi ( x -- value )
x 0 >= 1 -1 ? :> sign x abs 2 sqrt / :> x! p x * 1 +
recip :> t a5 t * a4 + t * a3 + t * a2 + t * a1 + t *
x x neg * e^ * 1 swap - :> y sign y * 1 + 2 / ;