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Let $X$ and $Y$ be isothermal parametrizations of minimal surfaces such that their component functions are pairwise harmonic conjugates, then $X$ and $Y$ are called conjugate minimal surfaces.

My question is: Are the helicoid and the catenoid conjugate minimal surfaces? It seems to be impossible after a short calculation.

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Yes, they are conjugate minimal surfaces.

I remember running into calculation errors when I first did this problem, too. The trick that worked for me was to rotate the helicoid by an angle of $\frac{\pi}{2}$. Hopefully you should still have isothermal coordinates (check this), but now the Cauchy-Riemann Equations will be satisfied (check this too).

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    One way to look at this $\pi / 2$ rotation is as a complex rotation in the [Weierstrass parametrization](http://en.wikipedia.org/wiki/Weierstrass%E2%80%93Enneper_parameterization).2011-04-06
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    That's pretty cool.2011-04-06