Trend Line Constants

[Guest]

I have created and X Y Scatter chart and placed an Exponential Trend Line on
it with a good R2 result. I have added the equation to be shown on the chart.

How can I put the Constant values of this equation into separate cells
within the worksheet.

i.e. equation is Y = bE (cX)

I want to put the value of "b" and "c" into separate cells. Can anyone help?

 

[Bill Martin]

I have created and X Y Scatter chart and placed an Exponential Trend Line on
it with a good R2 result. I have added the equation to be shown on the chart.

How can I put the Constant values of this equation into separate cells
within the worksheet.

i.e. equation is Y = bE (cX)

I want to put the value of "b" and "c" into separate cells. Can anyone help?

------------------

I don't believe you can capture the constants simply from the graph. However,
ask the Excel help system about the LOGEST( ) function which will provide them.

Bill

 

[Guest]

Hi,

Assuming that your x-values are in A2:A21 and y-values are in B2:B21, use
the following formulas to calculate b and c.

For b, =EXP(INTERCEPT(LN(B2:B21),A2:A21))
For c, =SLOPE(LN(B2:B21),(A2:A21))

Regards,
B. R. Ramachandran

 

[Jerry W. Lewis]

David Braden has posted code to extract coefficients from the chart
trendline equation

http://groups.google.com/group/microsoft.public.excel.misc/msg/4d440d271303e0d6

You must format the equation to display full precision (scientific w/ 14
decimal places) or you will lose accuracy.

Jerry

 

[Guest]

Many thanks B. R.Ramachandran, this worked fantastically!!!! KEN

 

[Guest]

B.R. Ramachandran

Thanks for your help on this one. Also I need to get a Polynomial constants
for a 2 degree equation. Can you help? e.g. Z = aX(2) + bX + c.
I need a, b and c