Thanks Tom & Dana,
I'll play with David's code next weekend.
:):) Tom I know I've been busy.
:):) But to smooth my consience a bit.
I still help people a lot with physical acoustics in studio groups.
In Excel I'm still stuck with a lot of old macro4 programs.
Dana,
checking your function, it seems I still must search how to make those
formulas for n numbers of x.
Must take some time to better understand.
Warm regards
Eric
"Dana DeLouis" wrote in message
...
Eric. Just for feedback, David's code works really well! For example, he
gave 7 data points for testing, with x values running from 1-7.
As a custom function, the Cubic Spline equations of that test data would
be
the following: The returned values match David exactly. :)
Function Spline(num)
Dim t, n
n = num - Int(num)
Select Case num
Case Is < 1
t = "#N/A"
Case Is < 2
t = 3 + (21 * n) / 26 - (21 * n ^ 3) / 26
Case Is < 3
t = 3 - (21 * n) / 13 - (63 * n ^ 2) / 26 + (53 * n ^ 3) / 26
Case Is < 4
t = 1 - (9 * n) / 26 + (48 * n ^ 2) / 13 - (61 * n ^ 3) / 26
Case Is < 5
t = 2 - (87 * n ^ 2) / 26 + (61 * n ^ 3) / 26
Case Is < 6
t = 1 + (9 * n) / 26 + (48 * n ^ 2) / 13 - (53 * n ^ 3) / 26
Case Is <= 7
t = 3 + (21 * n) / 13 - (63 * n ^ 2) / 26 + (21 * n ^ 3) / 26
Case Else
t = "#N/A"
End Select
Spline = t
End Function
--
Dana DeLouis
Win XP & Office 2003
"Eric Desart" wrote in message
...
Hello Debra,
A million thanks .... that one works.
I tried again in Ron de Bruyn's Google search and via Google.com by
literally copying text from the David Braden post as text and they
couldn't
find it.
You helped me a lot.
And thanks to David to.
Kind regards
Eric
PS: maybe an idea for David to reenter that post that google.com can
find
it
too. (it's often referred to).
"Debra Dalgleish" wrote in message
...
Try this link instead:
http://groups.google.ca/groups?selm=...chester.rr.com
Eric Desart wrote:
Sorry all,
A dumb question.
I was searching the Excel groups for a Cubic spline smoothing.
I find numerous messages refering to code entered by David Braden.
In some I find a link:
Most (all?) look like this:
http://groups.google.com/groups?selm...chester.rr.com
But this leads nowhere.
Can somebody help me locating this code?
I really tried myself.
TIA
Eric
--
Debra Dalgleish
Excel FAQ, Tips & Book List
http://www.contextures.com/tiptech.html