GPOF Method approximation Problem

Hi,
I have followed a paper for General Pencil of Function (GPOF) method and wrote a matlab code accordingly, I tried to approximate some known functions like cos and exponential, and for a certain sampling space of the function, the Cos and exponential functions are approximated very well, but when i tried to do the same for Sin function, the approximation is going out of phase, Can any one guide me here to know where i possibly made a mistake.

Thank you.

To check the validity of code : take one modulated signal and see if this decomposes those frequencies.