In mathematics, a number of concepts employ the word harmonic. The similarity of this terminology to that of music is not accidental: the equations of motion of vibrating strings, drums and columns of air are given by formulas involving Laplacians; the solutions to which are given by eigenvalues corresponding to their modes of vibration.

See

• harmonic analysis
• harmonic form
• harmonic function
• harmonic mean
• harmonic number
• harmonic series