Curve Fitting a Function to known X & Y data
 

Hi,

I would like to curve-fit the function

(y+d)^2= a+b*(x-c)/ln(x-c)

to X and Y data I have. I would like to know coefficients a,b,c,d,r^2 and
the maximum slope of the function. It is also important for me to see a graph
illustrating both the function and first derivative.

So far I have been doing this using "Tablecurve 2d", but I would like to
built this into a template in order to automate this process (I have over
5000 data files).

Thanks!

Curve Fitting a Function to known X & Y data
 

Walter -

To do the curve fit in Excel, you would probably have to use Excel's Solver
to search changing cells a, b, c, and d that minimize a target cell
containing a formula for sum of squared deviations. Then use formulas for
r^2 and estimates of the derivative. And plot the results using an XY
(Scatter) chart or two. And, it could all be automated using VBA.

But it might be easier to use code provided by Systat, and use a platform
other than Excel.

- Mike Middleton
http://www.DecisionToolworks.com
Decision Analysis Add-ins for Excel



"Walter" wrote in message
...
Hi,

I would like to curve-fit the function

(y+d)^2= a+b*(x-c)/ln(x-c)

to X and Y data I have. I would like to know coefficients a,b,c,d,r^2 and
the maximum slope of the function. It is also important for me to see a
graph
illustrating both the function and first derivative.

So far I have been doing this using "Tablecurve 2d", but I would like to
built this into a template in order to automate this process (I have over
5000 data files).

Thanks!

Curve Fitting a Function to known X & Y data
 

Thanks a lot for your help Mike. I'll try doing that.

"Mike Middleton" wrote:

Walter -

To do the curve fit in Excel, you would probably have to use Excel's Solver
to search changing cells a, b, c, and d that minimize a target cell
containing a formula for sum of squared deviations. Then use formulas for
r^2 and estimates of the derivative. And plot the results using an XY
(Scatter) chart or two. And, it could all be automated using VBA.

But it might be easier to use code provided by Systat, and use a platform
other than Excel.

- Mike Middleton
http://www.DecisionToolworks.com
Decision Analysis Add-ins for Excel



"Walter" wrote in message
...
Hi,

I would like to curve-fit the function

(y+d)^2= a+b*(x-c)/ln(x-c)

to X and Y data I have. I would like to know coefficients a,b,c,d,r^2 and
the maximum slope of the function. It is also important for me to see a
graph
illustrating both the function and first derivative.

So far I have been doing this using "Tablecurve 2d", but I would like to
built this into a template in order to automate this process (I have over
5000 data files).

Thanks!