A set that is not convex is called a non-convex set. A polygon that is not a convex polygon is sometimes called a concave polygon, and some sources more generally use the term concave set to mean a non-convex set, but most authorities prohibit this usage.
In either case you don't need to deal with the absolute value. A rectified sine wave is a periodic signal with a period equal to half of the full sinusoid, I would write the sine in exponential form and integrate over one period to find the series coefficients.
A sine wave is a good example of a repeating pattern of amplitudes, and in some ways it is the simplest. Thats why sine waves are sometimes referred to as simple harmonic motions. Lets arbitrarily fix an amplitude scale to be from â1 to 1, so the sine wave goes from 0 to 1 to 0 to â1 to 0. sine wave is a good example of a repeating pattern of amplitudes, and in some ways it is the simplest. Thats why sine waves are sometimes referred to as simple harmonic motions. Lets arbitrarily fix an amplitude scale to be from â1 to 1, so the sine wave goes from 0 to 1 to 0 to â1 to 0.