Machine-translated by Google. Questions are authored in English.
Top

Discussion

True or false: a function whose real and imaginary parts are both harmonic must be analytic.

  • A.True, harmonicity of both parts being equivalent to analyticity
  • B.True, provided the region is simply connected
  • C.True, unless the function is unbounded in the region
  • D.False, the two parts also having to satisfy the Cauchy-Riemann equations

Answer: D

Harmonicity of each part is necessary but not sufficient: the two must be conjugate, that is linked by the Cauchy-Riemann equations. Taking \( u = x \) with \( v = y \) gives two harmonic functions, yet \( x + iy \) written that way is \( \bar{z} \)'s cousin and fails the equations, so the pairing matters as much as the parts

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.