The hyperbolic sine and the hyperbolic cosine are entire functions. This relation between sine and cosine is sometimes called the fundamental Pythagorean trigonometric identity. The modulation is accomplished by varying the sine and cosine inputs at a precise time. Their length can be calculated by a common sine or cosine function. Note that the inverse sine and cosine functions yield two possible values for the argument. Any number that is the sine or cosine of a rational multiple of pi. In complex analysis, the hyperbolic functions arise as the imaginary parts of sine and cosine. A sine wave is a continuous wave. A Wien bridge oscillator is a type of electronic oscillator that generates sine waves. The resultant wave very roughly resembles the shape of a sine wave. Additive synthesis most directly generates sound by adding the output of multiple sine wave generators. One measure of the purity of a sine wave is the total harmonic distortion (THD). In 1821, Fresnel derived formulae equivalent to his sine and tangent laws Eqs. These cards used FM synthesis, which generates sound through modulation of sine waves. It has 32 algorithms, each a different arrangement of its six sine wave operators.