Re: summing up incrementally

> > The increase over three years is 1.03 * 1.02 * 1.08 =~ 1.135 or 13.5%
> > so you will need a recursive template as xpath2 doesn't have a product
> > built in (or you could use saxon7's implementation of xpath 2 draft,
> > which does)
>
> Actually, I am not working with interest on a loan. I am working with
> the gross sales of chain stores. Each month in December the statistics
> give the percentage of increase from the previous year. So if in 1934
> the store increased its sales 5 percent, and then in 1935 increased it 7
> percent, the total increase from 1933 is 12 percent. I'm using the
> percent from a periodical, but I don't think the periodical adjusted for
> inflation, so I may have to do some additional math.
>
> But I get the idea of sum--thanks!

It is quite simple to see that the real comulative increase is the product
of percentages of yearly increases, not their sum.

E.g. two yearly increases of 50% each give 225% comulative increase. That is
1.5 x 1.5, or it may be calculated:

In case the value is 100 at start, it would be 150 after year 1.

An increase of 50% the second year is 50% of 150 -- that is 75.

The value at the end of the second year is 150 + 75 = 225

Therefore, the total increase is:  225/100 = 2.25 = 225%

Your approach to calculating the total increase is wrong -- e.g. in the
above case it woud give 100%, not 225%.



Dimitre Novatchev.
FXSL developer

http://fxsl.sourceforge.net/ -- the home of FXSL
Resume: http://fxsl.sf.net/DNovatchev/Resume/Res.html


Dimitre Novatchev.
FXSL developer

http://fxsl.sourceforge.net/ -- the home of FXSL
Resume: http://fxsl.sf.net/DNovatchev/Resume/Res.html




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