how to fit a trend line in plotyy ?

 % code
y = [1:120]';
plotyy(y,data1,y,data2);
hold on
% plot(y,intercept + slope*y);

according to this code how can fit a trend line in data2

Answer 1

[Brendan Hamm]

You could use:

p = polyfit(y,data1,n); % looks like you want n=1 in your case

p contains the coefficients of the line:

fitLine = p(1)*y + p(2);

or equivalently:

fitLine = polyfit(p,y);

Answer 2

[Image Analyst]

See my attached polyfit demo.