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Curve-fit hyperbolic function in Excel?

Gary Rudnick rudnick at biomed.med.yale.edu
Wed Sep 14 13:47:36 EST 1994


>On Tue, 13 Sep 1994, Lawrence P. Casson wrote:

>> Is anyone aware of a macro or plugin for Excel that will fit data points
>> to a hyperbolic function (ie. y=A*x/(1+B*x) )?  If necessary, I'll attempt
>> one myself, but if one is available, so much the better.  I'm attempting
>> to plot flourescence quenching data and to estimate Q-max.  I figure that
>> anything that can be implemented in Excel can be used by everyone in my
>> lab.
>> 
>> Thanks,
>> Larry
>> 
>> lpcasson at phoenix.princeton.edu
>> 
>> -- 
>> Lawrence P. Casson
>> lpcasson at phoenix.princeton.edu
>> 
>> 
>> 
I always did this by using the solver.  You create 2 columns 
with your real data, x and y, and a third column with y(i) 
calculated using x(i) and the equation you want.  The 
parameters for the equation are stored in some other cells.  
Now make another column which contains the absolute difference 
between the real and calculated y values and at the bottom of 
that column, the sum of the differences.  The solver can vary 
the parameters to minimize the sum of the differences.  
Good Luck!

================================================================
Gary Rudnick                       |voice (203) 785-4548
Department of Pharmacology         |fax (203) 785-7670
Yale University School of Medicine |bitnet RUDNICK at YALEMED
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