addScaledSH( sh, s ) {

		for ( let i = 0; i < 9; i ++ ) {

			this.coefficients[ i ].addScaledVector( sh.coefficients[ i ], s );

		}

		return this;

	}
A convenience method for performing {@link SphericalHarmonics3#add} and
{@link SphericalHarmonics3#scale} at once.

@param {SphericalHarmonics3} sh - The SH to add.
@param {number} s - The scale factor.
@return {SphericalHarmonics3} A reference to this spherical harmonics.