This is a cross-post

Hello;

The following is a failed attempt for the sum of a simple series:

The series formula is:
f(X) = Sum [k=1 to k=m+1] a(k)*X^(k-1)

Example:
lower limit in cell $B$7:: 1
value of m in cell $B$8:: 3
(m+1) values of a(k) in col B starting (always) cell B11
..........a(1) in cell B11:: -1.899
..........a(2) in cell B12:: 2.50
..........a(3) in cell B13:: 3.699
.....a(m+1) in cell B14:: -3.121
(address of last cell in col B is in cell B32:: (B14 for this example)
value of X in cell $I$11:: 2.0
Retuned Sum value in cell I34::should be -7.071 ...

The array formula entered in I34:
{=SUM(PRODUCT(B11:B32, POWER(I11,ROW(INDIRECT(B7&":"&B8+1))-1)))}

returns the wrong sum of 54.807 ...
(Product and Power functions are used so that they could be replaced (if the
need arise) with their complex number counterparts)

The problem with the above formula is that apparently it multiplies the
elements of the 1st array: B11*B12*B13*B14 instead of summing the product of
the corresponding elements: B11*I11^0 + B12*I11^1 + B13*I11^2 + B14*I11^3
The 1st argument B11:B32 of the Product function is clearly the problem.
The 2nd argument should be OK. I think!

Your suggestion to fix the above array formula would be greatly appreciated.

Regards.