Array ente
=MMULT(LINEST($E$1:$E$16,$D$1:$D$16^{1,2,3},TRUE,F ALSE),TRANSPOSE(D1^{3,2,1,0}))
where E1:E16 contain the y values, D1:D16 the x values.

To array enter a formula complete entry not with the ENTER key but the
CTRL+SHIFT+ENTER combination.

Of course, you would be better off having XL calculate the LINEST result
only once. Enter the result of the LINEST in a range and then use an array
formula like
=MMULT($G$1:$J$1,TRANSPOSE(D1^{3,2,1,0}))
where G1:J1 contains the result of the LINEST formula.

--

Tushar Mehta
http://www.tushar-mehta.com
Custom business solutions leveraging a multi-disciplinary approach
In Excel 2007 double-click to format may not work; right click and select
from the menu


"Brad Carman" wrote:

Does anyone have a suggestion of how I can enter the following array formula
into Excel in a much simpiler way?

=INDEX(LINEST(TaveRNG,TimeRNG^{1,2,3}),1)*Time^3+I NDEX(LINEST(TaveRNG,TimeRNG^{1,2,3}),2)*Time^2+IND EX(LINEST(TaveRNG,TimeRNG^{1,2,3}),3)*Time+INDEX(L INEST(TaveRNG,TimeRNG^{1,2,3}),4)

To explain:
LINEST(TaveRNG,TimeRNG^{1,2,3}) returns an array of coefficients {a,b,c,d}
for my curve fit
y = a*x^3 + b*x^2+c*x+d

I have a feeling that this could be entered into excel something like:
=SUM(LINEST(A1:A10,B1:B10^{1,2,3})*{B1^3,B1^2,B1,1 })
except I can't build an array between brackets { } with a reference to a
cell, this only works with constants.

Do I need to create a custom UDF to handle something like this?