/* REXX       SQRT        deliver the square root of the given number.
                          If nested PUSH onto queue, else SAY.

     Modification History
     20211121 fxc eliminate extraneous trailing zeroes (and if
                     necessary) trailing decimal point;
     20250312 fxc wrap with SHORTRX; enable tracing; check DIFF vs
                  ABS(lastdiff); if nested, PUSH root;
     20250325 fxc must keep check for diff = lastdiff;

*/ arg argline                         /* pro-forma quick-start      */
address TSO
arg parms "((" opts
opts = Strip( opts,'T','5d'x )
parse var opts "TRACE"  tv  .
parse value tv "N"  with  tv .
rc = Trace("O"); rc = Trace(tv)

/* REXX external subroutine computes square roots.

   Original by (probably) Robin Ryerse

.  ----------------------------------------------------------------- */
SQRT:                                  /*@                           */
parse var parms  nbr  .
deflt  = Digits()
parse var nbr whole "." frac
if \Datatype(whole,"W") then whole = 0
if \Datatype(frac ,"W") then frac  = 0; else frac = "."frac
if Length(whole)//2 = 0 then parse var whole base 3 tail
                        else parse var whole base 2 tail
root = (base/2) * (10**(Length(tail)%2)) + frac
numeric digits 12
lastdiff = 0
do forever
   diff = nbr - root**2
   if diff = 0 then leave
   if diff =      lastdiff   then leave
   if diff = ABS( lastdiff ) then leave
   lastdiff = diff
   root  =  root + ((diff/2) /root)
end
numeric digits deflt
root = root + 0
root = Strip( root,"T","0" )
root = Strip( root,"T","." )
if Sysvar("Sysnest") = "NO" then say root; else,
push   root                            /*@ SQRT                      */

exit                                   /*@ SQRT                      */