How do I specify the limits of parameters individually while fitting?

On top of not knowing how to specifically limit 1 parameter to positive numbers, I get this error for my custom model:

Error using

fittype/testCustomModelEvaluation

(line 16)

Custom equations must produce an

output vector, matrix, or array that

is the same size and shape as the

input data. This custom equation

fails to meet that requirement:

m*exp(-d/x)*x.^2

Here is my code:

data = readmatrix('nagn125.txt');

vv=data(:,1);

ii=data(:,2);

pos=vv>0; neg=~pos;

gpos=fittype(@(m,c,d,x) m*exp(-c)*exp(-d/x)*x.^2);

options=fitoptions('exp(-d/x)','Lower',0);

plot(fneg,vv(neg),ii(neg))

grid('on')

Answer 1

[Nagasai Bharat]

Hi,

Change the fittype statement to that of below. This should solve the error you are getting

gpos=fittype(@(m,c,d,x) m.*exp(-c).*exp(-d./x).*x.^2);