02-10-2008, 09:16 PM
W0001 LBL W
W0002 x<>y
W0003 STO A
W0004 x<>y
W0005 STO B
W0006 1
W0007 +
W0008 LN
W0009 STO X
W0010 FN= F
W0011 SOLVE X
W0012 RCL A
W0013 x<>y
W0014 RTN
F0001 LBL F
F0002 RCL X
F0003 ex
F0004 LASTx
F0005 *
F0006 RCL- B
F0007 RTNW: LN=54; CK=C232
F: LN=21; CK=3529-e-1 <= x < 1E500
This basically uses the definition of Lambert's W function: W is the inverse function of f(w)=wew.
Its applications include solutions of equations involving exponentials. For instance, the solution of xx=2 is x=eWln(2)
On the HP-33s:
2 LN XEQ W ex -> 1.55961046946
The program is equivalent to Valentin Albillo's one-liner for the HP-71B in
HP-71B Math ROM Baker's Dozen (Vol. 1), but the HP-33s is slightly faster. I am not sure about the HP-35s.
Gerson.