How to curve fit custom equation with sigma function

Dear all,

I would like to get coefficient a, b, and c from the below equation,

Could you please let me know how I can write this equation in 'custom equation' option in curve fitting tool or is there any other way to do it?

the sample data was attached.

Many thanks in advance

[Alex Sha]

Hi, are the results below what you want?

Sum Squared Error (SSE): 0.00102105467088842
Root of Mean Square Error (RMSE): 0.00963447725094346
Correlation Coef. (R): 0.997357643506717
R-Square: 0.994722269061272

Parameter	Best Estimate     
---------	-------------     
a        	0.109551186277872 
b        	0.290413540962005 
c        	0.0381729804932852

[Abolfazl]

Hi, exactly, Many thanks for your time and kind help. Actually, I should fit a large amount of test results and I need custom equation or function file to fit another test results. could you please help to write it?

Answer 1

[Torsten]

Look at the example

Fit a Custom Model Using an Anonymous Function

under

https://de.mathworks.com/help/curvefit/fit.html

to see how you can specify your own fit function.

Specify your model function from above in a separate function file, not as a function handle.

[Abolfazl]

Thank you so much for your guide. It works.