[seqfan] Futurevalue considered harmful

franktaw at netscape.net franktaw at netscape.net
Sun Aug 16 20:58:41 CEST 2009

A look at the sequences using futurevalue seems to indicate that the 
programs were all submitted by the same person.  Since anyone else can 
do the same query, I will go ahead and give the name: Zerinvary Lajos.

(Specifically, a spot check found his name on every such program, and a 
search for 'maple:futurevalue -maple:"Zerinvary Lajos"' found only one 
match, a sequence that he submitted.)

It appears that only a minority of these programs use the form 
'futurevalue(x,c1,c2)' where c1 and c2 are constants.  Certainly all 
these should be eliminated in favor of evaluating c=(1+c1)^c2 and 
changing the program to c*x, with further simplification as 
appropriate.  In some cases, the result will then essentially duplicate 
a program already present, in which case it should be deleted.

The remaining ones really also seem pretty marginal, from what I looked 
at.  Indeed, a number of Zerinvary's other programs in the database 
seem to be cute tricks (i.e., obfuscation), not serious programs that 
someone might actually want to use.  Insofar as this is true, he should 
stop it.

So, I guess my final opinion is to agree that all these programs using 
futurevalue should be replaced or removed.

Incidentally, someone (I've lost track of who) made the comment (I'm 
paraphrasing) that business analysts aren't very sophisticated 
mathematically, and might use an expression like futurevalue(x,2,2) 
without realizing that this is the same as 9*x.  In fact, this is not 
at all true; these expressions are dealing with MONEY, and it is very 
important to understand just what an expression means.  And any 
business analyst certainly knows that futurevalue(x,y,z) = x*(1+y)^z, 
and can evaluate (1+2)^2.  (In fact, the first thing our hypothetical 
business analyst is going to do on seeing "futurevalue" is to 
investigate the definition to see whether it is x*(1+y)^z or 
x*(1+y/100)^z; he or she would probably prefer the latter.)

Franklin T. Adams-Watters

More information about the SeqFan mailing list