Error in non-linear regression

I am trying to prepare a non-linear reg model with the following variables in the following way: sea ~ sst + at

I am receiving an error when applying the beta) function and the fitnlm function. So far, this is what I've done:

t=readtable('ban1.csv')

sea=t(:,2)

sst=t(:,3)

at=t(:,4)

tbl=table(sea,sst,at)

modelfun = @(b,x)b(1) + b(2)*sst + b(3)*at;

When i try to apply the beta0:

beta0 = 10*rand(var,1);

I get the error:

Not enough input arguments.

Error in var (line 65) if isinteger(x)

And when i tried beta0 = [-50 500 -1 500 -1]; mdl = fitnlm(tbl,modelfun,beta0);

I get the following errors:

Error using classreg.regr.FitObject/selectVariables (line 289) Predictor variables must be numeric vectors or matrices.

Error in NonLinearModel/selectVariables (line 1157) model = [e-mail](model);

Error in classreg.regr.FitObject/doFit (line 91) model = selectVariables(model);

Error in NonLinearModel.fit (line 1434) model = doFit(model);

Error in fitnlm (line 99) model = NonLinearModel.fit(X,varargin{:});

I would be grateful if someone could help me with this problem, preferably with the code. I have attached the csv file. Thanks!

Answer 1

[Torsten]

t = readtable('ban1.csv')
sea = t(:,2)
sst = t(:,3)
at = t(:,4)
A = [ones(numel(sea),1),sst,at];
rhs = sea;
b = A\rhs

give you the parameters you are looking for.

Best wishes

Torsten.

[Keegan Carvalho]

Thanks @Torsten. I still am getting some errors.

>> A = [ones(numel(sea),1),sst,at]; All input arguments must be tables.

>> rhs = sea; >> b = A\rhs Undefined function or variable 'A'.

Also, how do I know what the equation?

Please excuse my questions, as I am a beginner in this.