My graph is displaying source data ='E3 Live '!$AK$1037:$AK$2168 and the
trendlines equation is y=.6954e^(-0.0001x). In my excel the formula
"=EXP(INTERCEPT(LN(AK1037:AK2168),A1037:A2168) )" result in 0.802566202,
shouldn't it result in 0.6954???


"Mike Middleton" wrote:

bastien86 -

For a solution using worksheet functions, to get the coefficients for
Excel's exponential trendline function with form y = c*EXP(b*x),

c = EXP(INTERCEPT(LN(yrange),xrange))
b = SLOPE(LN(yrange),xrange)

For a specific yvalue, the corresponding x on the fitted curve is

x = (LN(yvalue)-LN(c))/b

So, if you put the formulas for c and b in worksheet cells, and if the
formula for x has cell references to those cells and to a cell where you
specify a yvalue, then c and b and x will update dynamically when you
respecify the yrange or xrange.

- Mike
www.mikemiddleton.com


"bastien86" wrote in message
...
Is there a way to insert the equation of my trendline into calculations in
my
worksheet. The rate is always changing each passing day due to more
collected data... I wish to give a daily projection on when the certain
maximum is going to be reached, which is goign to always be changing
because
of the changing trendline. Can I make reference to a data sereis
trendline
ie.

y=10e^5x

x = hours

is there a way i can calculate x for a set y? and if the trendline
changes,
then so does the value of x?