How I got a and b value from cftool in MATLAB by this equation
y=ln[q*tsi*ltw*a]-exp(b/x), where rest of the parameter values are
q=1.6*10^-19
tsi=10*10^-9
ltw=0.04583
x=[1.91E-05 1.36E-05 1.11E-05 9.62E-06 8.62E-06 7.87E-06 7.30E-06 6.80E-06 6.41E-06];
y=-[86.00 78.00 74.00 72.00 71.00 70.00 69.00 68.00 67.00];
please help me to find out a and b
Just rewrite your given equation in the standard form for linear regression ... like
Y = A + B*X,
where A, B, X and Y are appropriately related to the corresponding given empirical values.
Good luck
btw, you may certainly "ignore" the empirical value ln[q*tsi*ltw] because, simply, it is going to offset the value of ln(a), which you may call 'a' in the calculations with the cftool ...
so, as soon as you have x-and-y data in Matlab, you run the cftool like this
>> x=[1.91E-05 1.36E-05 1.11E-05 9.62E-06 8.62E-06 7.87E-06 7.30E-06 6.80E-06 6.41E-06]';
>> y=-[86.00 78.00 74.00 72.00 71.00 70.00 69.00 68.00 67.00]';
>> cftool( x, y )
and, ... set your 'custom' equation like this (see attachment '1')
where, note the offset of b to b/1000 = done for numerical stability when running the cftool,
and don't miss the bounds (see attachment '2')
...
thus you are done
... results are in '11' attachment (again)
however,
note that a simply linear regression has much better R-square
just see '22'
Good luck
visit this --> https://www.mathworks.com/matlabcentral/answers/1902310-how-i-got-a-and-b-value-from-cftool-in-matlab
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