Accounting for Phase difference

I have got phase difference between harmonics of a sine wave as below. If I want to reconstruct the sine wave from its harmonics amplitude and phase, how do I consider the phase difference which is not an integer multiple of pi. I know that if it is odd multiple of pi, it is destructive interference and the waves should be opposite in sign. and if the phase difference is even multiple of pi, it is instructive intereference and waves are added together. What if phase difference is 1.5 multiple of pi?

phase difference.

0 -1.570796326794896 -3.141592653589793 -4.712388980384689 -6.283185307179585 -7.853981633974482 -9.424777960769378 -10.995574287564274 -12.566370614359171 -14.137166941154067 -15.707963267948964 -17.278759594743860 -18.849555921538755 -20.420352248333653 -21.991148575128548.

(0π, -1/2π, -π, -3/2π, -2π......)

[Bjorn Gustavsson]

You are allowed to write your function (not "a sine-wave" if you have this many harmonics) something like this:

so dont get too stuck on multiples of pi/2. Then start to use the complex exponential - which in the long run will remove a whole lot of thinking when it comes to sines-cosines and such, everything becomes more automatic...

[Syed AWM]

Thanks for that. What if I need the harmonics' amplitude with their sign for any other purpose rather than regenerating the sine wave. what would be the sign of harmonics with a phase difference of 1.5pi. (The sign is important in my case)

[Bjorn Gustavsson]

For that case I'll give you the complex answer:

[Syed AWM]

exp(i*7*pi) gives: -1 + 0.000000000001i. does that mean the sign is would be positive as I have got +0.0000000001i?