Original function

Transformed function

u ( x ) = u 1 ( x ) ± u 2 ( x )

U ( k ) = U 1 ( k ) ± U 2 ( k )

u ( x ) = c v ( x )

U ( k ) = c V ( k )

u ( x ) = u 1 ( x ) u 2 ( x )

U ( k ) = m = 0 k U 1 ( m ) U 2 ( k m )

u ( x ) = k v ( x ) x k

U ( k ) = ( k + m ) ! k ! V ( k + m )