HP 50G: Function KST - What Does It Do?

[Gerald H]

Some years ago I programmed a function

KST (I guess the name has some relevance)

Code:


::
  CK2&Dispatch
  2REAL
  ::
    2%>%%
    %%1
    %%2
    4PICK
    %%2
    %%^
    %%*
    %%CHS
    %%EXP
    %%1
    %%2
    6ROLL
    %%3
    7ROLL
    %%SQRT
    %%*
    %%/
    %%*
    %%-
    %%*
    %%-
    %%>%
  ;
;

which for input X, Y calculates

1-(1/EXP(2*X^2))*(1-2*(X/(3*√Y)))

Can anyone say the use of the function?