# Harmonic function

1. Jan 24, 2008

while doing physics , i just stuck on problem regarding mathematics

i wanted to plot the graph of combined SHM but in the formula there is a big problem regarding finding the angle of the given tangent.

i first used inverse tan but got a very weird wave, later i realized that inverse tan can give solutions between 0 -$$\pi$$ but what i wanted was a continuous increase in angle.
i.e > $$\pi$$or2*$$\pi$$, as angle increases with time(x -axis)

can somebody tell how to find angle

2. Jan 24, 2008

### HallsofIvy

Staff Emeritus
Your calculator is giving the "principal value", specifically that value of t between $-\pi$ and $\pi$. Since tangent is periodic with period $\pi$ your other values will be that number, plus $\pi$, plus $2\pi$, plus $3\pi$, etc.

3. Jan 24, 2008