Hello stata users,

I am trying to perform a cosinor analysis to determine the effect of season on iodine dispersion.
Here is my code:
Array
This code produces this graph:
Array

The problem is that I am trying to produce a graph similar to the one pictured here:
Array
(plucked from https://www.statalist.org/forums/forum/general-stata-discussion/general/1223983-trigonometric-regression)

but I cannot seem to get this code to produce a graph like this. Does anyone have any suggestions?


Thank you for your time and help!!