Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!mcdchg!tellab5!ram
From: ram@tellabs.com (Bob Martin)
Newsgroups: comp.sys.handhelds
Subject: Possible bug with ISOL and SOLVE
Message-ID: <4155@tellab5.tellabs.com>
Date: 11 Oct 90 22:56:48 GMT
Sender: news@Tellabs.COM
Organization: Tellabs, Inc. Lisle IL
Lines: 37

I was playing around with some equations and learning about ISOL, when I ran
across the following situation:

2:  'PV=PMT*((1-(1+INTPP)^-NUMP)/INTPP)'
1:  'NUMP'
execute ISOL

I expect:  1:  'NUMP=-(LN(1-PV/PMT*INTPP)/LN(1+INTPP))'

but I get: 1:  'NUMP=-((LN(1-PV/PMT*INTPP)+2*pi*i*n1)/LN(1+INTPP))'

Now, I get confused by the "2*pi*i*n1" term, so I diligently search the manual
for an explanation.  On pg. 393 I find out about general and principal solutions
and how flag -1 affects this.  Fine.  I also learn what n1 is - an arbitrary
integer.  Now the paragraph below that states that when I set flag -1 to get
principal solutions, n1 will be set to zero (hence removing that term).  So
instead of redoing the ISOL with -1 set, I go into SOLVR anyway, and set n1 = 0.
When I solve for NUMP (having supplied sane values for PV, INTPP, and PMT),
I get an error - "Bad guess(es)".  ????  What's going on?  So I edit the
equation to remove the "+2*pi*i*n1" term, go back into SOLVR and recalculate,
and everything works fine.  So now I surmise that the 48 has a problem
evaluating 2*pi*i*0.  To check this, I enter '2*pi*i*n1' into the stack.
I store 0 in n1 and hit EVAL, and I get ...... 0!  I try storing 1 in n1 and
EVAL .... '2*pi*i'!!   So what in the world is going on here?

Please help, I am very confused!


=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Bob Martin		|  ram@tellabs.com	...!uunet!tellab5!ram
Tellabs, Inc.		|   "Listen to me now, and believe me later"
Lisle, IL.  60532	|		-  Hans und Franz
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=--=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Bob Martin		|  ram@tellabs.com	...!uunet!tellab5!ram
Tellabs, Inc.		|   "Listen to me now, and believe me later"
Lisle, IL.  60532	|		-  Hans und Franz