my graph won't show the exponential graph as the alpha value is 0, can someone help fix this problem?

%a

cockrach=importdata('cockroach_population.xlsx');

num_cockrach=cockrach.data;

days=num_cockrach(:,1);

cockraches=num_cockrach(:,2);

%b

ylin=cockraches;

xlin=log(days);

[a0,a1,r2] = linreg(xlin,ylin);

p=polyfit(days,cockraches,2);

alpha=(exp(1)).^a0;

Beta=a1;

text1=sprintf('parabola-cockraches rate: cockraches= %.2fx^2+%.2fx+%.2f',p);

%c

exponential_curve= alpha.*exp(1).^(Beta.*days);

text2=sprintf('exponential-cockraches rate: cockraches= %.2fe^%.2fx\n',alpha, Beta);

figure

plot(days,cockraches,'b.');

hold on

plot(days,polyval(p,days),'r-','LineWidth',3);

plot(days,exponential_curve,'g-','LineWidth',3)

title('numbers of cockraches vs times(days)');

xlabel('cockraches');

ylabel('days');

legend('unlinearised',text1,text2)

[Elisa]

i found that the a0 vlues will be the same value as the exponential e(1), which is why that causes alpha to be 0, but how to fix this probleM?

[nick]

Hi @Elisa,

Kindly please attach the XLSX file 'cockroach_population' which will help in resolving the query effectively.

[Elisa]

I think i found the problem, thank you！

[Torsten]

@Elisa

It's not wrong, but better use exp(x) instead of exp(1).^x in your code.