some problems with lsquares



Hello,

Many  thanks for this very useful contribution.
I observe one problem when I tried to find an approximation with lsquares. 
Why the numerics is left unevaluated in the following case?
(C22)   
lsquares(m6,[o,a,dia],dia=k1+ok2*atan(o)/o+ak2*atan(a)/a+k2*atan(o)*atan(a)/(o*a),
(C22)   [k1,ok2,ak2,k2]);

       Determination Coefficient = 0.83294990112697
(D22) dia = (51446713433530427328677360728845969736736885578*ATAN(a)*ATAN(o)
          -455999762562121434746193650304046751931462692880*a*ATAN(o)
          +(1238808364074986242512306422589519959308270339712*a
           -4057697611201546716146647006983806762760711262080*ATAN(a))
           *o)
          /(91095585936884748220570072249110905420450590459571*a*o)
(C23) expand(bfloat(rhs(%)));

(D23) 5.647552831942384B-4*ATAN(a)*ATAN(o)/(a*o)
       -5.005728410134595B-3*ATAN(o)/o-4.454329558857998B-2*ATAN(a)/a
       +1.359899441157654B-2

Well I can simplify d22 with c23.  However, I have a problem when I give the 
approximation in the more complicated form.  I  obtain the diagnostic like,
 5144671343353042732869(many numbers) is not a fixnum kind.

best rgds,
valery