# MATLAB: How to parametrize two parameters in an equation

parametrize

I have observed relative humidity and a statistical method to estimate RH. The statistical method uses two different parameters and I would like to use the observations to parametrize the two parameters (the parameters are supposed to be around 2.1 for a and 0.130 for ab).
What I have done so far is;
best_total_dist=10000000000;best_a=100;best_ab=100;hum=log(rh); % rh is observed relative humidity for a=0:0.01:2.3    for ab=0:0.001:0.0150    estrh=10.^(a-(ab.*t)); % statistical method to estimate relative humidity     difference=estrh-hum;    difference_sq=difference.^2;    sum_difference=sum(difference_sq);    if sum_difference<best_total_dist        best_total_dist=sum_difference;        best_a=a;        best_ab=ab;    end    endend
Where am I going wrong?

#### Best Answer

• According to your code, the model for 'rh' (not log(rh)) is going to be
rh = exp(10.^(a-(ab.*t)))
That's a doubtful looking model to me. At t=0, it means that rh=4.7254e+54.
If I assume that you really meant,
log(rh)= a-(ab.*t)
then you could find the least squares solution by
 x=[ones(size(t)),  -t]\log(rh); a=x(1); ab=x(2);